t210: Add PINMUX macros for drive strength

t210: Add PINMUX macros for drive strength

BUG=chrome-os-partner:41877
BRANCH=None
TEST=Compiles successfully and boots to kernel prompt

Change-Id: Ic606838639d33242b227fece9cbb019d8f3b3729
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 805831489ad80e4ed335ece458f81238af704876
Original-Change-Id: I54a730c3b97c3603a5b1981089913c58af2a42db
Original-Signed-off-by: Furquan Shaikh <furquan@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/284958
Original-Tested-by: Furquan Shaikh <furquan@chromium.org>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
Original-Trybot-Ready: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/10944
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>