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/drivers/pci/pci_indirect.c b/drivers/pci/pci_indirect.c
index 526a55c..aee0bd6 100644
--- a/drivers/pci/pci_indirect.c
+++ b/drivers/pci/pci_indirect.c
@@ -3,10 +3,7 @@
  *
  * Copyright (C) 1998 Gabriel Paubert.
  *
- * 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+
  */
 
 #include <common.h>