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/calxedaxgmac.c b/drivers/net/calxedaxgmac.c
index e3553d6..2c61710 100644
--- a/drivers/net/calxedaxgmac.c
+++ b/drivers/net/calxedaxgmac.c
@@ -1,19 +1,9 @@
 /*
  * Copyright 2010-2011 Calxeda, Inc.
  *
- * 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 in the hope 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.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program.  If not, see <http://www.gnu.org/licenses/>.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
+
 #include <common.h>
 #include <malloc.h>
 #include <linux/compiler.h>