mediatek: Share mtcmos code among similar SOCs

Refactor mtcmos code which will be reused among similar SOCs.

BUG=b:80501386
BRANCH=none
TEST=Boots correctly on Elm

Change-Id: Ibfd0a90f6eba3ed2e74a3fd54279c7645aa41774
Signed-off-by: Tristan Shieh <tristan.shieh@mediatek.com>
Reviewed-on: https://review.coreboot.org/27028
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
4 files changed