[media] uapi/media.h: Declare interface types for V4L2 and DVB

Declare the interface types that will be used by the new
G_TOPOLOGY ioctl that will be defined later on.

For now, we need those types, as they'll be used on the
internal structs associated with the new media_interface
graph object defined on the next patch.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>