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/evb64260/eth.c b/board/evb64260/eth.c
index a3a3276..d7f63bd 100644
--- a/board/evb64260/eth.c
+++ b/board/evb64260/eth.c
@@ -4,10 +4,7 @@
 ***************************************************************************/
 
 /*
- * 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, or (at
- * your option) any later version.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 /*