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 <florian@openwrt.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: stable <stable@kernel.org>

drivers/watchdog/mtx-1_wdt.c

@@ -214,6 +214,12 @@ static int __devinit mtx1_wdt_probe(struct platform_device *pdev)
 	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);
@@ -239,6 +245,8 @@ static int __devexit mtx1_wdt_remove(struct platform_device *pdev)
 		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;
 }