[media] v4l: vdev_to_v4l2_subdev() should have return type "struct v4l2_subdev *"

vdev_to_v4l2_subdev() should return struct v4l2_subdev *, not void *. Fix
this.
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

include/media/v4l2-subdev.h

@@ -545,7 +545,7 @@ struct v4l2_subdev {
 #define media_entity_to_v4l2_subdev(ent) \
 	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
-	video_get_drvdata(vdev)
+	((struct v4l2_subdev *)video_get_drvdata(vdev))
 
 /*
  * Used for storing subdev information per file handle