mediatek: Move uart, timer and cbmem code to a common directory.

This patch moves uart, timer and cbmem code which can be reused into a
common directory under soc/mediatek.

BUG=b:80501386
BRANCH=none
TEST=the refactored code works fine on the new platform (with the rest
     of the patches applied) and Elm platform

Change-Id: I5210149b324947ee90f1a481b42f0e2e1f7cfc25
Signed-off-by: Tristan Shieh <tristan.shieh@mediatek.com>
Reviewed-on: https://review.coreboot.org/26658
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
5 files changed