EC software sync: Split up EC and auxfw sync

Currently, the logic for updating auxfw is entangled with the logic
for performing EC software sync.  This patch attempts to split them
apart, so that they can be used separately.  VbSelectAndLoadKernel()
currently still performs both, EC first and then auxfw.  The intended
use-case for this functionality is to perform EC software sync only in
coreboot's romstage.  Unit tests were updated to ensure functionality
is effectively unchanged.

BUG=b:143094352, chromium:1016688
BRANCH=none
TEST=make clean && make runtests

Change-Id: I7bdf38694cfed83b18dd8189b8516780184ecc8e
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1867314
Reviewed-by: Julius Werner <jwerner@chromium.org>
12 files changed