cr50: Add support for hwtimer

Implement the API expected by common/timer.c

BUG=chrome-os-partner:33699
BRANCH=none
TEST=manual

Run the "gettime" and "timerinfo" and "taskinfo" and "waitms"
commands. Compare the elapsed time with the real world. They seem
to match.

Change-Id: Ie5acae76780ee09e7dfb6cc0282de25f8063e96f
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/229642
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
2 files changed