detachables: Ensure keyboard input in TO_DEV menu trusted

Add in check at TO_DEV menu screen to make sure that the navigation
keys (up/down, volup/voldown) are trusted.  Beep when user tries to
use unstrusted keys (usb keyboard) in the TO_DEV menu so that the user
knows they're doing something wrong.  USB keyboard return key will
still work in the TO_DEV menu.

BUG=b:65546569
BRANCH=None
TEST=test out using up/down keys in TO_DEV menu and make sure that
     they are disabled and hear beeps.

Change-Id: Ifc7183c7ca35efaf079abb196a90ab7305380642
Signed-off-by: Shelley Chen <shchen@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/665355
Reviewed-by: Julius Werner <jwerner@chromium.org>
1 file changed