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/keymile/km83xx/km83xx.c b/board/keymile/km83xx/km83xx.c
index faaa39b..b5ea7ae 100644
--- a/board/keymile/km83xx/km83xx.c
+++ b/board/keymile/km83xx/km83xx.c
@@ -11,10 +11,7 @@
  * (C) Copyright 2008 - 2010
  * Heiko Schocher, DENX Software Engineering, hs@denx.de.
  *
- * 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.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>