nb/intel/x4x: Implement resume from S3 suspend

It rewrites the results of receive enable stored in the upper nvram
region, to avoid running receive enable again.

Some debug info is also printed about the self-refresh registers.
(Not enforcing a reset here, since 0 does not necessarily mean it's
not in self-refresh).

Change-Id: Ib54bc5c7b0fed6d975ffc31f037b5179d9e5600b
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/17998
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
7 files changed