target/xtensa: replace FSF postal address with licenses URL

Some of the GPLv2 boiler-plate still contained the
obsolete "51 Franklin Street" postal address.

Replace it with the canonical GNU licenses URL recommended by the FSF:
https://www.gnu.org/licenses/

Signed-off-by: Sean Wei <me@sean.taipei>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Message-ID: <20250613.qemu.patch.11@sean.taipei>
Signed-off-by: Thomas Huth <thuth@redhat.com>

target/xtensa/core-dc232b/gdb-config.c.inc

@@ -15,9 +15,8 @@
    GNU General Public License for 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 02110-1301, USA.  */
+   along with this program; if not, see
+   <https://www.gnu.org/licenses/>.  */
 
   XTREG(0,   0, 32, 4, 4, 0x0020, 0x0006, -2, 9, 0x0100, pc,
           0, 0, 0, 0, 0, 0)

target/xtensa/core-dc232b/xtensa-modules.c.inc

@@ -14,9 +14,8 @@
    General Public License for 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
-   02110-1301, USA.  */
+   along with this program; if not, see
+   <https://www.gnu.org/licenses/>.  */
 
 #include "qemu/osdep.h"
 #include "xtensa-isa.h"

target/xtensa/core-fsf/xtensa-modules.c.inc

@@ -14,9 +14,8 @@
    General Public License for 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
-   02110-1301, USA.  */
+   along with this program; if not, see
+   <https://www.gnu.org/licenses/>.  */
 
 #include "qemu/osdep.h"
 #include "xtensa-isa.h"