nb/x4x: Get rid of device_t

Use of `device_t` has been abandoned in ramstage.

Change-Id: Ib3e708a7fa9f0a78dc704a502a2f01ee0fe209ae
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/23655
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
4 files changed