[media] v4l2-subdev: remove enum_framesizes/intervals

The video and pad ops are duplicates, so get rid of the more limited video op.

The whole point of the subdev API is to allow reuse of subdev drivers by
bridge drivers. Having duplicate ops makes that much harder. We should never
have allowed duplicate ops in the first place. A lesson for the future.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>