vboot2: add a flag to indicate firmware was selected by vboot2

TEST=Done manually on Nyan:
  localhost ~ # sudo /tmp/crossystem fw_vboot2
  0
  localhost ~ # sudo /tmp/crossystem fw_vboot2=1
  localhost ~ # sudo /tmp/crossystem fw_vboot2
  0
  # reboot with vboot2 firmware
  localhost ~ # /tmp/crossystem fw_vboot2
  1

BUG=none
BRANCH=none
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

Change-Id: I6ed553c48bdfebf07393f6f5f46832a60971314a
Reviewed-on: https://chromium-review.googlesource.com/205664
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
3 files changed