Add check for preventing invalid key in FAFT_STEP.

To avoid any typo of the key.

BUG=chromium-os:19710
TEST=run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
         servo_vid=0x18d1 servo_pid=0x5001" TryFwB/control.normal

Change-Id: I58cd25c7366265148f2c4d3a69c7d5880a696c4e
Reviewed-on: https://gerrit.chromium.org/gerrit/12965
Reviewed-by: Todd Broch <tbroch@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
1 file changed