vboot2: api-level routines

I'm breaking the last chunk of vboot2 into smaller pieces as I add
tests.  This has the api-level routines actually called by depthcharge.

BUG=chromium:370082
BRANCH=none
TEST=make clean && VBOOT2=1 COV=1 make

Change-Id: Ic7c082fc5faa0b874b2fa5a15ebda7135dcafe0b
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/200151
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
6 files changed