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/cpu/ppc4xx/miiphy.c b/cpu/ppc4xx/miiphy.c
index 01710e7..6a92bf8 100644
--- a/cpu/ppc4xx/miiphy.c
+++ b/cpu/ppc4xx/miiphy.c
@@ -1,4 +1,6 @@
 /*-----------------------------------------------------------------------------+
+  |   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