faft: Move all constants of verified boot out to a module

It slims the FAFTSequence class and makes other non-FAFT tests reuse these
vboot constants.

BUG=chromium-os:32147
TEST=run the following tests passed:
run_remote_tests.sh --board link --remote dut control.faft_lv2
run_remote_tests.sh --board link --remote dut control.faft_lv3

Change-Id: I524d1ff2046e1e1826359c939f2d918426707141
Reviewed-on: https://gerrit.chromium.org/gerrit/34739
Reviewed-by: Mike Truty <truty@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
Commit-Ready: Brian Harring <ferringb@chromium.org>
19 files changed