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/sandburst/metrobox/init.S b/board/sandburst/metrobox/init.S
index be3f885..13e340e 100644
--- a/board/sandburst/metrobox/init.S
+++ b/board/sandburst/metrobox/init.S
@@ -1,24 +1,7 @@
 /*
 *  Copyright (C) 2005
 *  Travis B. Sawyer, Sandburst Corporation, tsawyer@sandburst.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., 59 Temple Place, Suite 330, Boston,
-* MA 02111-1307 USA
+ * SPDX-License-Identifier:	GPL-2.0+
 */
 
 #include <ppc_asm.tmpl>