[media] media-device: Simplify compat32 logic

Only MEDIA_IOC_ENUM_LINKS32 require an special logic when
userspace is 32 bits and Kernel is 64 bits.

For the rest, media_device_ioctl() will do the right thing,
and will return -ENOIOCTLCMD if the ioctl is unknown.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>