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/nvidia/ventana/Makefile b/board/nvidia/ventana/Makefile
index 147d0bc..9c2349d 100644
--- a/board/nvidia/ventana/Makefile
+++ b/board/nvidia/ventana/Makefile
@@ -2,24 +2,7 @@
 #  (C) Copyright 2010,2011
 #  NVIDIA Corporation <www.nvidia.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 $(TOPDIR)/config.mk