CHROMIUM: mkbp: add keyboard driver

CHROMIUM: mkbp: add keyboard driver

This adds the Matrix Keyboard Protocol driver to kernel 3.4.
This driver is used by Chrome devices.

BUG=chrome-os-partner:8917
TEST=ran the factory keyboard test

Change-Id: I1f3ecd9add0f4a954ed524cccdb7980df06938bd
Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Reviewed-on: https://gerrit-int.chromium.org/17756
Commit-Ready: Luigi Semenzato <semenzato@google.com>
Tested-by: Luigi Semenzato <semenzato@google.com>
Reviewed-by: Olof Johansson <olofj@google.com>