media: uvcvideo: Constify video_subdev structures

uvc_subdev_ops is only passed as the second argument of
v4l2_subdev_init, which is const, so uvc_subdev_ops can be
const as well.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/usb/uvc/uvc_entity.c

@@ -61,7 +61,7 @@ static int uvc_mc_create_links(struct uvc_video_chain *chain,
 	return 0;
 }
 
-static struct v4l2_subdev_ops uvc_subdev_ops = {
+static const struct v4l2_subdev_ops uvc_subdev_ops = {
 };
 
 void uvc_mc_cleanup_entity(struct uvc_entity *entity)