serial: imx: disable UCR4_OREN on shutdown

UCR4_OREN is (depending on the configuration) enabled in startup,
but is never disabled. Fix this by disabling it in shutdown.
Reported-by: Nandor Han <nandor.han@ge.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -1422,7 +1422,7 @@ static void imx_uart_shutdown(struct uart_port *port)
 {
 	struct imx_port *sport = (struct imx_port *)port;
 	unsigned long flags;
-	u32 ucr1, ucr2;
+	u32 ucr1, ucr2, ucr4;
 
 	if (sport->dma_is_enabled) {
 		dmaengine_terminate_sync(sport->dma_chan_tx);
@@ -1452,6 +1452,10 @@ static void imx_uart_shutdown(struct uart_port *port)
 	ucr2 = imx_uart_readl(sport, UCR2);
 	ucr2 &= ~(UCR2_TXEN | UCR2_ATEN);
 	imx_uart_writel(sport, ucr2, UCR2);
+
+	ucr4 = imx_uart_readl(sport, UCR4);
+	ucr4 &= ~UCR4_OREN;
+	imx_uart_writel(sport, ucr4, UCR4);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 
 	/*