fix firmware tests for vboot2

vboot2 stays in slot B as long as it's good and valid. some tests such as
RollbackFirmware fail because they assume the firmware prefers slot A, thus,
expect mainfw_act is A after reboot.

vboot1 firmware should not be affected by this change.

BUG=chrome-os-partner:32193
BRANCH=ToT
TEST=Ran faft on Nyan Blaze and Kitty

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Change-Id: I116c13772dd2158c330dbcf7a8002c0fbb4fc3a3
Reviewed-on: https://chromium-review.googlesource.com/231378
Reviewed-by: Yusuf Mohsinally <mohsinally@chromium.org>
5 files changed