driver core: Skip unnecessary work when device doesn't have sync_state()

A bunch of busy work is done for devices that don't have sync_state()
support. Stop doing the busy work.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200221080510.197337-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

@@ -718,6 +718,8 @@ static void __device_links_queue_sync_state(struct device *dev,
 {
 	struct device_link *link;
 
+	if (!dev_has_sync_state(dev))
+		return;
 	if (dev->state_synced)
 		return;
 
@@ -819,7 +821,7 @@ late_initcall(sync_state_resume_initcall);
 
 static void __device_links_supplier_defer_sync(struct device *sup)
 {
-	if (list_empty(&sup->links.defer_sync))
+	if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(sup))
 		list_add_tail(&sup->links.defer_sync, &deferred_sync);
 }