Add GPL-2.0+ SPDX-License-Identifier to source files

Signed-off-by: Wolfgang Denk <wd@denx.de>
[trini: Fixup common/cmd_io.c]
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/board/ti/ti814x/Makefile b/board/ti/ti814x/Makefile
index 09d2422..6059e20 100644
--- a/board/ti/ti814x/Makefile
+++ b/board/ti/ti814x/Makefile
@@ -3,15 +3,7 @@
 #
 # Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
 #
-# 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; either version 2 of
-# the License, or (at your option) any later version.
-#
-# This program is distributed "as is" WITHOUT ANY WARRANTY of any
-# kind, whether express or implied; without even the implied warranty
-# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU General Public License for more details.
+# SPDX-License-Identifier:	GPL-2.0+
 #
 
 include $(TOPDIR)/config.mk