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/include/lmb.h b/include/lmb.h
index 43082a3..6b6959f 100644
--- a/include/lmb.h
+++ b/include/lmb.h
@@ -8,10 +8,7 @@
  *
  * Copyright (C) 2001 Peter Bergner, IBM Corp.
  *
- * 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.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #define MAX_LMB_REGIONS 8