firmware_FAFTSetup: Add spec checking mode

In spec checking mode, test actions are directly controlled on servo.
This is used to test if a device meets all the testability requirements.

If this test is run with parameter -a "spec_check=True", then hardware
testability is checked according to spec and without any current workaround.

BUG=chrome-os-partner:14649
TEST=Pass on link.

Change-Id: Ibbeda4d9137ab5d04d977d2acd895ab1bf940078
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/34270
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
2 files changed