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/drivers/net/xilinx_ll_temac.c b/drivers/net/xilinx_ll_temac.c
index b67153b..dab78d0 100644
--- a/drivers/net/xilinx_ll_temac.c
+++ b/drivers/net/xilinx_ll_temac.c
@@ -11,10 +11,7 @@
  * Copyright (C) 2008 Nissin Systems Co.,Ltd.
  * March 2008 created
  *
- * 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+
  *
  * [0]: http://www.xilinx.com/support/documentation
  *