serial/imx: disable hardware flow control at startup

We only want to enable hardware flow control if RTS/CTS pins
are connected.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -761,6 +761,8 @@ static int imx_startup(struct uart_port *port)
 
 	temp = readl(sport->port.membase + UCR2);
 	temp |= (UCR2_RXEN | UCR2_TXEN);
+	if (!sport->have_rtscts)
+		temp |= UCR2_IRTS;
 	writel(temp, sport->port.membase + UCR2);
 
 	if (USE_IRDA(sport)) {