vboot: Fix linking error with USE_OPTION_TABLE enabled

Fix a linking problem with VBOOT and USE_OPTION_TABLE enabled.
Make use of cbfs_locate_file_in_region() and always search the
cmos_layout.bin in the 'COREBOOT' region.

With this change applied there's no need to include the vboot_locator
in SMM any more, we can't break NVRAM with different CMOS layouts,
and we keep VBOOT and non VBOOT behaviour the same.

Only include cmos_layout.bin and cmos.default in RO region.

Add notes explaining the decisions.

Tested on Intel Sandybridge, builds and boots with vboot enabled.

Change-Id: I10ae94d7936581bbb5ea49384122062bd4934ea5
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/26863
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
3 files changed