lenovo/t420: Add new port

This is based on t420s. Tested on a T420 without discrete GPU.
There is no support for nvidia gpu and optimus.

Signed-off-by: Nicolas Reinecke <nr@das-labor.org>
Tested-by: Iru Cai <mytbk920423@gmail.com>
Change-Id: Ie9405966e56180ac1c43a3c5b83181ee500177c8
Reviewed-on: https://review.coreboot.org/11765
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/mainboard/lenovo/t420/Makefile.inc b/src/mainboard/lenovo/t420/Makefile.inc
new file mode 100644
index 0000000..9eb141a
--- /dev/null
+++ b/src/mainboard/lenovo/t420/Makefile.inc
@@ -0,0 +1,17 @@
+##
+## This file is part of the coreboot project.
+##
+## Copyright (C) 2011 The ChromiumOS Authors.  All rights reserved.
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; version 2 of the License.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+
+smm-$(CONFIG_HAVE_SMI_HANDLER) += smihandler.c
+romstage-y += gpio.c