USB: mct_u232: fix broken close

Fix regression introduced by commit
f26788da (USB: serial: refactor generic
close) which broke driver close().

This driver uses non-standard semantics for the read urb which makes the
generic close function fail to kill it (the read urb is actually an
interrupt urb and therefore bulk_in size is zero).
Reported-by: Eric Shattow "Eprecocious" <lucent@gmail.com>
Tested-by: Eric Shattow "Eprecocious" <lucent@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/mct_u232.c

@@ -549,9 +549,12 @@ static void mct_u232_close(struct usb_serial_port *port)
 {
 	dbg("%s port %d", __func__, port->number);
 
-	usb_serial_generic_close(port);
-	if (port->serial->dev)
+	if (port->serial->dev) {
+		/* shutdown our urbs */
+		usb_kill_urb(port->write_urb);
+		usb_kill_urb(port->read_urb);
 		usb_kill_urb(port->interrupt_in_urb);
+	}
 } /* mct_u232_close */