device property: Advertise fwnode and device property count API calls

The documentation of fwnode and device property array API calls isn't
pointing out to the shortcuts to count the number of elements of size
in an array. Amend the documentation to advertise fwnode and device
property count API calls.

Reported-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/property.c

@@ -68,6 +68,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_present);
  * Function reads an array of u8 properties with @propname from the device
  * firmware description and stores them to @val if found.
  *
+ * It's recommended to call device_property_count_u8() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -93,6 +96,9 @@ EXPORT_SYMBOL_GPL(device_property_read_u8_array);
  * Function reads an array of u16 properties with @propname from the device
  * firmware description and stores them to @val if found.
  *
+ * It's recommended to call device_property_count_u16() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -118,6 +124,9 @@ EXPORT_SYMBOL_GPL(device_property_read_u16_array);
  * Function reads an array of u32 properties with @propname from the device
  * firmware description and stores them to @val if found.
  *
+ * It's recommended to call device_property_count_u32() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -143,6 +152,9 @@ EXPORT_SYMBOL_GPL(device_property_read_u32_array);
  * Function reads an array of u64 properties with @propname from the device
  * firmware description and stores them to @val if found.
  *
+ * It's recommended to call device_property_count_u64() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -168,6 +180,9 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
  * Function reads an array of string properties with @propname from the device
  * firmware description and stores them to @val if found.
  *
+ * It's recommended to call device_property_string_array_count() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values read on success if @val is non-NULL,
  *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,
@@ -256,6 +271,9 @@ static int fwnode_property_read_int_array(const struct fwnode_handle *fwnode,
  * Read an array of u8 properties with @propname from @fwnode and stores them to
  * @val if found.
  *
+ * It's recommended to call fwnode_property_count_u8() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -282,6 +300,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u8_array);
  * Read an array of u16 properties with @propname from @fwnode and store them to
  * @val if found.
  *
+ * It's recommended to call fwnode_property_count_u16() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -308,6 +329,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u16_array);
  * Read an array of u32 properties with @propname from @fwnode store them to
  * @val if found.
  *
+ * It's recommended to call fwnode_property_count_u32() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -334,6 +358,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u32_array);
  * Read an array of u64 properties with @propname from @fwnode and store them to
  * @val if found.
  *
+ * It's recommended to call fwnode_property_count_u64() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
@@ -360,6 +387,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u64_array);
  * Read an string list property @propname from the given firmware node and store
  * them to @val if found.
  *
+ * It's recommended to call fwnode_property_string_array_count() instead of calling
+ * this function with @val equals %NULL and @nval equals 0.
+ *
  * Return: number of values read on success if @val is non-NULL,
  *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,