The label property is defined as optional in the DFSDM binding.
Parse the label property only when it is defined in the device tree.

Fixes: 3208fa0cd919 ("iio: adc: stm32-dfsdm: adopt generic channels bindings")
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/iio/adc/stm32-dfsdm-adc.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index 2037f73426d4..e304e3714020 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -691,11 +691,14 @@ static int stm32_dfsdm_generic_channel_parse_of(struct stm32_dfsdm *dfsdm,
 		return -EINVAL;
 	}
 
-	ret = fwnode_property_read_string(node, "label", &ch->datasheet_name);
-	if (ret < 0) {
-		dev_err(&indio_dev->dev,
-			" Error parsing 'label' for idx %d\n", ch->channel);
-		return ret;
+	if (fwnode_property_present(node, "label")) {
+		/* label is optional */
+		ret = fwnode_property_read_string(node, "label", &ch->datasheet_name);
+		if (ret < 0) {
+			dev_err(&indio_dev->dev,
+				" Error parsing 'label' for idx %d\n", ch->channel);
+			return ret;
+		}
 	}
 
 	df_ch =  &dfsdm->ch_list[ch->channel];
-- 
2.25.1