gpio: sifive: add missing check for platform_get_irq

Add the missing check for platform_get_irq() and return error code
if it fails.

The returned error code will be dealed with in
builtin_platform_driver(sifive_gpio_driver) and the driver will not
be registered.

Fixes: f52d6d8b43 ("gpio: sifive: To get gpio irq offset from device tree data")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-sifive.c

@@ -221,8 +221,12 @@ static int sifive_gpio_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	for (i = 0; i < ngpio; i++)
-		chip->irq_number[i] = platform_get_irq(pdev, i);
+	for (i = 0; i < ngpio; i++) {
+		ret = platform_get_irq(pdev, i);
+		if (ret < 0)
+			return ret;
+		chip->irq_number[i] = ret;
+	}
 
 	ret = bgpio_init(&chip->gc, dev, 4,
 			 chip->base + SIFIVE_GPIO_INPUT_VAL,