[media] adv7604: Add support for asynchronous probing

Register the device with the v4l2 asynchronous probing framework to
support asynchronous instantiation systems such as DT.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/i2c/adv7604.c

@@ -2333,6 +2333,11 @@ static int adv7604_probe(struct i2c_client *client,
 		goto err_entity;
 	v4l2_info(sd, "%s found @ 0x%x (%s)\n", client->name,
 			client->addr << 1, client->adapter->name);
+
+	err = v4l2_async_register_subdev(sd);
+	if (err)
+		goto err_entity;
+
 	return 0;
 
 err_entity:
@@ -2356,6 +2361,7 @@ static int adv7604_remove(struct i2c_client *client)
 
 	cancel_delayed_work(&state->delayed_work_enable_hotplug);
 	destroy_workqueue(state->work_queues);
+	v4l2_async_unregister_subdev(sd);
 	v4l2_device_unregister_subdev(sd);
 	media_entity_cleanup(&sd->entity);
 	adv7604_unregister_clients(to_state(sd));