driver core: Add dev_has_sync_state()

Add an API to check if a device has sync_state support in its driver or
bus.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200221080510.197337-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/device.h

@@ -798,6 +798,17 @@ static inline struct device_node *dev_of_node(struct device *dev)
 	return dev->of_node;
 }
 
+static inline bool dev_has_sync_state(struct device *dev)
+{
+	if (!dev)
+		return false;
+	if (dev->driver && dev->driver->sync_state)
+		return true;
+	if (dev->bus && dev->bus->sync_state)
+		return true;
+	return false;
+}
+
 /*
  * High level routines for use by the bus drivers
  */