vboot: Modify VbExIsShutdownRequested to return shutdown request mask

Change to VbExIsShutdownRequested required to support
GBB_FLAG_DISABLE_LID_SHUTDOWN in vboot.

BUG=chromium:434462
BRANCH=Auron
TEST=Manual on Auron, with corresponding vboot_reference change. Set GBB
flag 0x1000 and disable powerd launch on boot. Close lid and issue
'reboot' command over ssh. Verify system reboots successfully into OS.
CQ-DEPEND=CL:234995

Change-Id: Ie8019e0297e44e6922e5337fcfd07cd7d61d8639
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/234994
Reviewed-by: Randall Spangler <rspangler@chromium.org>
(cherry picked from commit 9d35da53cfac3d5a6e5cfdb5192f17496f8c8e4d)
Reviewed-on: https://chromium-review.googlesource.com/234983
1 file changed