serial: clps711x: fail if mctrl_gpio_init fails

mctrl_gpio_init is fully aware of being optional. If it returns an error
code this indicates a real error that must not be ignored.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/clps711x.c

@@ -501,6 +501,8 @@ static int uart_clps711x_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, s);
 
 	s->gpios = mctrl_gpio_init(&pdev->dev, 0);
+	if (IS_ERR(s->gpios))
+	    return PTR_ERR(s->gpios);
 
 	ret = uart_add_one_port(&clps711x_uart, &s->port);
 	if (ret)