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/freescale/mx51evk/imximage.cfg b/board/freescale/mx51evk/imximage.cfg
index aaa490a..a3b8593 100644
--- a/board/freescale/mx51evk/imximage.cfg
+++ b/board/freescale/mx51evk/imximage.cfg
@@ -2,23 +2,7 @@
  * (C Copyright 2009
  * Stefano Babic DENX Software Engineering sbabic@denx.de.
  *
- * 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. 51 Franklin Street Fifth Floor Boston,
- * MA 02110-1301 USA
+ * SPDX-License-Identifier:	GPL-2.0+
  *
  * Refer doc/README.imximage for more details about how-to configure
  * and create imximage boot image