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/usb/ulpi/ulpi.c b/drivers/usb/ulpi/ulpi.c
index 23b59e7..f3d1856 100644
--- a/drivers/usb/ulpi/ulpi.c
+++ b/drivers/usb/ulpi/ulpi.c
@@ -17,15 +17,7 @@
  *   Sascha Hauer <s.hauer@pengutronix.de>
  *   Freescale Semiconductors
  *
- * 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 that 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.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>