md: fix typo in FSF address

Hello,

 I found a typo Bosto"m" in FSF address.
And I am checking around linux source code.
Here is the only place which uses Bosto"m" (not Boston).

Signed-off-by: Atsushi SAKAI <sakaia@jp.fujitsu.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid6x86.h b/drivers/md/raid6x86.h
index 99fea7a..4c22c15 100644
--- a/drivers/md/raid6x86.h
+++ b/drivers/md/raid6x86.h
@@ -5,7 +5,7 @@
  *   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, Inc., 53 Temple Place Ste 330,
- *   Bostom MA 02111-1307, USA; either version 2 of the License, or
+ *   Boston MA 02111-1307, USA; either version 2 of the License, or
  *   (at your option) any later version; incorporated herein by reference.
  *
  * ----------------------------------------------------------------------- */