[media] v4l2-subdev: drop unused op enum_mbus_fmt

Weird, this op isn't used at all. Seems to be orphaned code.
Remove it.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

include/media/v4l2-subdev.h

@@ -342,8 +342,6 @@ struct v4l2_subdev_video_ops {
 			struct v4l2_dv_timings *timings);
 	int (*enum_mbus_fmt)(struct v4l2_subdev *sd, unsigned int index,
 			     u32 *code);
-	int (*enum_mbus_fsizes)(struct v4l2_subdev *sd,
-			     struct v4l2_frmsizeenum *fsize);
 	int (*g_mbus_fmt)(struct v4l2_subdev *sd,
 			  struct v4l2_mbus_framefmt *fmt);
 	int (*try_mbus_fmt)(struct v4l2_subdev *sd,