nb/intel/gm45: Get rid of device_t

Use of `device_t` has been abandoned in ramstage.

Change-Id: If064a4027265e8fc2ea919d9742a554abf29b8db
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/23667
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
4 files changed