sb/intel/i82801gx: Add the option to lock the platform

This allows to lock down spi among other things
Mostly copied from bd82x6x.

Tested on Intel DG41WV with the MRC_CACHE driver write protecting the
mrc_cache region.

Change-Id: If9c3a6118f4586d51c093edec896c347ba904b8f
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/23358
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
3 files changed