iio: dac: ad5770r: Put fwnode in error case during ->probe()

device_for_each_child_node() bumps a reference counting of a returned variable.
We have to balance it whenever we return to the caller.

Fixes: cbbb8198 ("iio: dac: ad5770r: Add AD5770R support")
Cc: Alexandru Tachici <alexandru.tachici@analog.com>
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Link: https://lore.kernel.org/r/20210510095649.3302835-1-andy.shevchenko@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ad5770r.c

@@ -524,23 +524,29 @@ static int ad5770r_channel_config(struct ad5770r_state *st)
 	device_for_each_child_node(&st->spi->dev, child) {
 		ret = fwnode_property_read_u32(child, "num", &num);
 		if (ret)
-			return ret;
-		if (num >= AD5770R_MAX_CHANNELS)
-			return -EINVAL;
+			goto err_child_out;
+		if (num >= AD5770R_MAX_CHANNELS) {
+			ret = -EINVAL;
+			goto err_child_out;
+		}
 
 		ret = fwnode_property_read_u32_array(child,
 						     "adi,range-microamp",
 						     tmp, 2);
 		if (ret)
-			return ret;
+			goto err_child_out;
 
 		min = tmp[0] / 1000;
 		max = tmp[1] / 1000;
 		ret = ad5770r_store_output_range(st, min, max, num);
 		if (ret)
-			return ret;
+			goto err_child_out;
 	}
 
+	return 0;
+
+err_child_out:
+	fwnode_handle_put(child);
 	return ret;
 }