ACPI: battery: Increase maximum string length

On the Dell Inspiron 3505, the battery model name
is represented as a hex string containing seven numbers,
causing it to be larger than the current maximum string
length (32).
Increase this length to 64 to avoid truncating the string
in such cases. Also introduce a common define for the length.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/battery.c

@@ -42,6 +42,8 @@
 #define ACPI_BATTERY_STATE_CHARGING	0x2
 #define ACPI_BATTERY_STATE_CRITICAL	0x4
 
+#define MAX_STRING_LENGTH	64
+
 MODULE_AUTHOR("Paul Diefenbaugh");
 MODULE_AUTHOR("Alexey Starikovskiy <astarikovskiy@suse.de>");
 MODULE_DESCRIPTION("ACPI Battery Driver");
@@ -118,10 +120,10 @@ struct acpi_battery {
 	int capacity_granularity_1;
 	int capacity_granularity_2;
 	int alarm;
-	char model_number[32];
-	char serial_number[32];
-	char type[32];
-	char oem_info[32];
+	char model_number[MAX_STRING_LENGTH];
+	char serial_number[MAX_STRING_LENGTH];
+	char type[MAX_STRING_LENGTH];
+	char oem_info[MAX_STRING_LENGTH];
 	int state;
 	int power_unit;
 	unsigned long flags;
@@ -437,7 +439,7 @@ static int extract_package(struct acpi_battery *battery,
 		element = &package->package.elements[i];
 		if (offsets[i].mode) {
 			u8 *ptr = (u8 *)battery + offsets[i].offset;
-			u32 len = 32;
+			u32 len = MAX_STRING_LENGTH;
 
 			switch (element->type) {
 			case ACPI_TYPE_BUFFER: