vboot: Change VbExEc implementations to support RO update

This change will be used to support EC-RO software sync by allowing for
access to the readonly region of firmware. Currently only the writable
section is accessed by vboot using VB_SELECT_FIRMWARE_A and B.

TEST=built on jerry and check that the RO hash can be read and the image
can be updated.

Change-Id: Ic3942d86b65da3123798cfd11a78056f5dab6699
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/319213
Reviewed-by: Randall Spangler <rspangler@chromium.org>
4 files changed