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>

include/config_uncmd_spl.h

@@ -2,27 +2,7 @@
  * (C) Copyright 2012
  * Ilya Yanok, ilya.yanok@gmail.com
  *
- * See file CREDITS for list of people who contributed to this
- * project.
- *
- * 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.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc.
- *
- * We don't use any commands in SPL, but generic networking code
- * has some features enabled/disabled based on CONFIG_CMD_*
- * options. As we want a minimal set of features included
- * into network SPL image, we undefine some config options here.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #ifndef __CONFIG_UNCMD_SPL_H__