Use virtual dev-mode switch when told to.

If VbInit() is instructed to look at a virtual dev-mode switch, then it will
use value contained in the TPM's firmware space instead of a hardware GPIO
to determine if developer mode is enabled.

This change just makes it look. It doesn't provide a way to actually set
the value in the TPM. VbInit() isn't being told to look yet, either. Those
changes are coming.

BUG=chrome-os-partner:9706
TEST=none

The usual sanity-check applies:

  make
  make runtests

But to actually test that this stuff is working IRL requires special tweaks
to other components and monitoring the serial debug output from both EC and
CPU. We'll save the hands-on tests for when it's all done.

Change-Id: Ie485ad2180224e192238bf2a5dbf95bbcb9130f9
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/23067
Reviewed-by: Randall Spangler <rspangler@chromium.org>
10 files changed