serial: two branches the same in timbuart_set_mctrl()

CTS is a read only bit and we are to stop signal RTS if modem line
TIOCM_RTS is not set.

Thanks for suggestions by Richard Röjfors.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/serial/timbuart.c

@@ -220,7 +220,7 @@ static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	if (mctrl & TIOCM_RTS)
 		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
 	else
-		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
+		iowrite8(0, port->membase + TIMBUART_CTRL);
 }
 
 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)