[media] media-device: Use u64 ints for pointers

By using u64 integers and pointers, we can get rid of compat32
logic. So, let's do it!

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>