rambi: add initial rambi mainboard support

This is just a copy from bayleybay.

BUG=chrome-os-partner:23121
BRANCH=None
TEST=None

Change-Id: I283415be326e2d92e1e1bf7866954f17a7266edb
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/171940
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
21 files changed