media: v4l2: async: remove locking when initializing async notifier

There is no need to hold the list_lock when initializing the local
asd_list of a notifier. Remove the lock handling to simplify the code
and remove a potential LOCKDEP warning.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reported-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/v4l2-core/v4l2-async.c

@@ -424,11 +424,7 @@ static int v4l2_async_notifier_asd_valid(struct v4l2_async_notifier *notifier,
 
 void v4l2_async_notifier_init(struct v4l2_async_notifier *notifier)
 {
-	mutex_lock(&list_lock);
-
 	INIT_LIST_HEAD(&notifier->asd_list);
-
-	mutex_unlock(&list_lock);
 }
 EXPORT_SYMBOL(v4l2_async_notifier_init);