staging: rtl8712: Replace FSF mailing address by URL

* Fix checkpatch.pl output about not including the paragraph
  about writing to the Free Software Foundation's mailing address
Signed-off-by: Michael Hornung <mhornung.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/ieee80211.h

@@ -12,8 +12,7 @@
  * 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.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
+ * this program; if not, see <http://www.gnu.org/licenses/>.
  *
  * Modifications for inclusion into the Linux staging tree are
  * Copyright(c) 2010 Larry Finger. All rights reserved.