STOUT-FIRMWARE: Print warning in Ctrl-U when dev_boot_usb is not enabled.

Ctrl-U used to simply beep without messages for why it does not work (due to NV
data dev_boot_usb). Since the system is already in Developer mode, it should be
fine to provide some debug information otherwise we can spent time trying to
figure out why the firmware doesn't work.

BRANCH=stout
BUG=chrome-os-partner:14474
TEST=manual, test basic firmware functions.

Change-Id: Ic4e20fc2df7c1c2dd6fb425f066ebd55d9659ac2
Original-Change-Id: Iab20ecdb2e1c4e267b7257a7bd241006241ddf70
Reviewed-on: https://gerrit.chromium.org/gerrit/35917
Reviewed-by: Shawn Nematbakhsh <shawnn@google.com>
Tested-by: Shawn Nematbakhsh <shawnn@google.com>
1 file changed