[media] media controller: get rid of entity subtype on Kernel

Don't use anymore the type/subtype entity data/macros
inside the Kernel.

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