twostop: Skip kernel verification when built for U-Boot sandbox

It's not yet possible to verify the kernel in an Chromium OS image
with the Sandbox Version of U-Boot due to the lack of keys.  For now,
stub out the verification process and behave as if everything is ok:
Sandbox U-Boot is only interested in the selected kernel and boot mode
at this point.

BUG=chromium-os:32603
TEST=With this change, it's possible to get valid answers from
  vboot_twostop command with Sanbox U-Boot.

Change-Id: I3b1142889657315675eacd3a1d1448aeee7ccb62
Signed-off-by: Taylor Hutt <thutt@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/30256
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
1 file changed