[PARISC] Clarify pdc_stable license terms

pdc_stable.c is explicitly licensed under GPL version 2.

Signed-off-by: Thibaut VARENE <varenet@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

arch/parisc/kernel/pdc_chassis.c

@@ -5,9 +5,8 @@
  *    Copyright (C) 2002-2004 Thibaut VARENE <varenet@parisc-linux.org>
  *
  *    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.
+ *    it under the terms of the GNU General Public License, version 2, as
+ *    published by the Free Software Foundation.
  *
  *    This program is distributed in the hope that it will be useful,
  *    but WITHOUT ANY WARRANTY; without even the implied warranty of