CHROMIUM: mfd: add chromeos_ec driver to kernel 3.4

CHROMIUM: mfd: add chromeos_ec driver to kernel 3.4

This adds the chromeos-ec driver.

BUG=chrome-os-partner:8917
TEST=none (not configured yet)

Change-Id: I999b1d4cb89ce62900659eb0ad7ebbb883f09b50
Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Reviewed-on: https://gerrit-int.chromium.org/17751
Commit-Ready: Luigi Semenzato <semenzato@google.com>
Reviewed-by: Luigi Semenzato <semenzato@google.com>
Tested-by: Luigi Semenzato <semenzato@google.com>
Reviewed-by: Olof Johansson <olofj@google.com>