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/xilinx/ml507/xparameters.h b/board/xilinx/ml507/xparameters.h
index 1992fff..e30e592 100644
--- a/board/xilinx/ml507/xparameters.h
+++ b/board/xilinx/ml507/xparameters.h
@@ -4,18 +4,7 @@
  * This work has been supported by: QTechnology  http://qtec.com/
  * based on xparameters-ml507.h by Xilinx
  *
- * 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, see <http://www.gnu.org/licenses/>.
+ * SPDX-License-Identifier:	GPL-2.0+
 */
 
 #ifndef XPARAMETER_H