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/ppc440-generic/init.S b/board/xilinx/ppc440-generic/init.S
index 54f2d7f..4598a37 100644
--- a/board/xilinx/ppc440-generic/init.S
+++ b/board/xilinx/ppc440-generic/init.S
@@ -3,19 +3,8 @@
  *  Ricado Ribalda-Universidad Autonoma de Madrid-ricardo.ribalda@uam.es
  *  This work has been supported by: QTechnology  http://qtec.com/
  *
- *  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+
+ */
 
 #include <ppc_asm.tmpl>
 #include <config.h>