iio: dac: ad8801: Make use of the helper function dev_err_probe()

When possible use dev_err_probe help to properly deal with the
PROBE_DEFER error, the benefit is that DEFER issue will be logged
in the devices_deferred debugfs file.
Using dev_err_probe() can reduce code size, and the error value
gets printed.
Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Link: https://lore.kernel.org/r/20210928013902.1341-1-caihuoqing@baidu.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ad8801.c

@@ -123,10 +123,9 @@ static int ad8801_probe(struct spi_device *spi)
 	id = spi_get_device_id(spi);
 
 	state->vrefh_reg = devm_regulator_get(&spi->dev, "vrefh");
-	if (IS_ERR(state->vrefh_reg)) {
-		dev_err(&spi->dev, "Vrefh regulator not specified\n");
-		return PTR_ERR(state->vrefh_reg);
-	}
+	if (IS_ERR(state->vrefh_reg))
+		return dev_err_probe(&spi->dev, PTR_ERR(state->vrefh_reg),
+				     "Vrefh regulator not specified\n");
 
 	ret = regulator_enable(state->vrefh_reg);
 	if (ret) {
@@ -146,8 +145,8 @@ static int ad8801_probe(struct spi_device *spi)
 	if (id->driver_data == ID_AD8803) {
 		state->vrefl_reg = devm_regulator_get(&spi->dev, "vrefl");
 		if (IS_ERR(state->vrefl_reg)) {
-			dev_err(&spi->dev, "Vrefl regulator not specified\n");
-			ret = PTR_ERR(state->vrefl_reg);
+			ret = dev_err_probe(&spi->dev, PTR_ERR(state->vrefl_reg),
+					    "Vrefl regulator not specified\n");
 			goto error_disable_vrefh_reg;
 		}