Dual-license IBM code contributions

It was brought to our attention that U-Boot contains code derived from the
IBM OpenBIOS source code originally provided with some of the older PowerPC
4xx development boards.  As a result, the original license of this code has
been carried in the various files for a number of years in the U-Boot project.

IBM is dual-licensing the IBM code contributions already present in U-Boot
under either the terms of the GNU General Public License version 2, or the
original code license already present.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
diff --git a/board/esd/pci405/writeibm.S b/board/esd/pci405/writeibm.S
index 9f5c35b..4e319c1 100644
--- a/board/esd/pci405/writeibm.S
+++ b/board/esd/pci405/writeibm.S
@@ -1,5 +1,9 @@
 /*------------------------------------------------------------------------------+ */
 /* */
+/*       This source code is dual-licensed.  You may use it under the terms */
+/*       of the GNU General Public License version 2, or under the license  */
+/*       below.                                                             */
+/*                                                                          */
 /*       This source code has been made available to you by IBM on an AS-IS */
 /*       basis.  Anyone receiving this source is licensed under IBM */
 /*       copyrights to use it in any way he or she deems fit, including */