iio: adc: berlin2-adc: Add missing of_node_put() in error path

of_get_parent() will return a device_node pointer with refcount
incremented. We need to use of_node_put() on it when done. Add the
missing of_node_put() in the error path of berlin2_adc_probe();

Fixes: 70f1937911ca ("iio: adc: add support for Berlin")
Signed-off-by: Xiongfeng Wang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Cc: <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/berlin2-adc.c

···
 	int ret;
 
 	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
-	if (!indio_dev)
+	if (!indio_dev) {
+		of_node_put(parent_np);
 		return -ENOMEM;
+	}
 
 	priv = iio_priv(indio_dev);