[media] media: implement 32-on-64 bit compat IOCTL handling

Use the same handlers where the structs are the same. Implement a new
handler for link enumeration since struct media_links_enum is different on
32-bit and 64-bit systems.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>