watchdog: mtx1-wdt: request gpio before using it

Otherwise, the gpiolib autorequest feature will produce a WARN_ON():

WARNING: at drivers/gpio/gpiolib.c:101 0x8020ec6c()
autorequest GPIO-215
[...]

Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>
Cc: stable <[e-mail]>

drivers/watchdog/mtx-1_wdt.c

···
 	int ret;
 
 	mtx1_wdt_device.gpio = pdev->resource[0].start;
+	ret = gpio_request_one(mtx1_wdt_device.gpio,
+				GPIOF_OUT_INIT_HIGH, "mtx1-wdt");
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to request gpio");
+		return ret;
+	}
 
 	spin_lock_init(&mtx1_wdt_device.lock);
 	init_completion(&mtx1_wdt_device.stop);
···
 		mtx1_wdt_device.queue = 0;
 		wait_for_completion(&mtx1_wdt_device.stop);
 	}
+
+	gpio_free(mtx1_wdt_device.gpio);
 	misc_deregister(&mtx1_wdt_misc);
 	return 0;
 }