[media] V4L: add enum_mbus_fsizes video operation

Add enum_mbus_fsizes V4L2 subdevice video operation.
Signed-off-by: Qing Xu <qingx@marvell.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

include/media/v4l2-subdev.h

@@ -271,6 +271,8 @@ struct v4l2_subdev_video_ops {
 			struct v4l2_dv_timings *timings);
 	int (*enum_mbus_fmt)(struct v4l2_subdev *sd, unsigned int index,
 			     enum v4l2_mbus_pixelcode *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,