serial: altera_jtaguart: adding iounmap()

The driver does ioremap(port->mapbase, ALTERA_JTAGUART_SIZE),
but there is no any iounmap().

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/altera_jtaguart.c

@@ -478,6 +478,7 @@ static int altera_jtaguart_remove(struct platform_device *pdev)
 
 	port = &altera_jtaguart_ports[i].port;
 	uart_remove_one_port(&altera_jtaguart_driver, port);
+	iounmap(port->membase);
 
 	return 0;
 }