USB: mos7840: fix urb leak at release

commit 65a4cdbb upstream.

Make sure control urb is freed at release.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/mos7840.c

@@ -2661,6 +2661,7 @@ static void mos7840_release(struct usb_serial *serial)
 		mos7840_port = mos7840_get_port_private(serial->port[i]);
 		dbg("mos7840_port %d = %p", i, mos7840_port);
 		if (mos7840_port) {
+			usb_free_urb(mos7840_port->control_urb);
 			kfree(mos7840_port->ctrl_buf);
 			kfree(mos7840_port->dr);
 			kfree(mos7840_port);