gpio: Avoid using an invalid ofnode

Devices do not necessarily have nodes attached to them, since they can be
created from platdata. In SPL a devicetree may in fact not exist at all.

Check the node before using it. This avoids failure when OF_CHECKS is
enabled.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 5fc7cf8c ("gpio: add gpio-hog support")
Reviewed-by: Heiko Schocher <hs@denx.de>

drivers/gpio/gpio-uclass.c

@@ -1474,7 +1474,7 @@ static int gpio_post_bind(struct udevice *dev)
 	}
 #endif
 
-	if (CONFIG_IS_ENABLED(GPIO_HOG)) {
+	if (CONFIG_IS_ENABLED(GPIO_HOG) && dev_has_ofnode(dev)) {
 		struct udevice *child;
 		ofnode node;