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/arch/x86/include/asm/ist.h b/arch/x86/include/asm/ist.h
index 7e5dff1..0cdbb45 100644
--- a/arch/x86/include/asm/ist.h
+++ b/arch/x86/include/asm/ist.h
@@ -5,15 +5,7 @@
  * Include file for the interface to IST BIOS
  * Copyright 2002 Andy Grover <andrew.grover@intel.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, 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.
+  * SPDX-License-Identifier:	GPL-2.0+
  */