detachables: Add VbExDisplayMenu def to headless_stub

Left out definition of VbExDisplayMenu for devices
that don't use the display driver.

BUG=b:35585623
BRANCH=None
TEST=./build_packages --board=gale

Change-Id: Iabd56f26f5d1441f8a45b454b578fa54a4be5128
Signed-off-by: Shelley Chen <shchen@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/517310
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit 33f9ca8ce70fb4b451bcecfb68814c9a079ec32e)
Reviewed-on: https://chromium-review.googlesource.com/518985
Reviewed-by: Brian Sheehan <bsheehan@google.com>
Reviewed-by: Kan Yan <kyan@google.com>
Commit-Queue: Kan Yan <kyan@google.com>
Tested-by: Kan Yan <kyan@google.com>
1 file changed