serial: 8250: Don't check for mctrl_gpio_init() returning -ENOSYS

Now that the mctrl_gpio code returns NULL instead of ERR_PTR(-ENOSYS)
if CONFIG_GPIOLIB is disabled, we can safely remove this check.
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Acked-by: Uwe Kleine-Knig <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20190802100349.8659-4-frieder.schrempf@kontron.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_core.c

@@ -1026,10 +1026,8 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		if (!has_acpi_companion(uart->port.dev)) {
 			gpios = mctrl_gpio_init(&uart->port, 0);
 			if (IS_ERR(gpios)) {
-				if (PTR_ERR(gpios) != -ENOSYS) {
 				ret = PTR_ERR(gpios);
 				goto out_unlock;
-				}
 			} else {
 				uart->gpios = gpios;
 			}