iio: light: gp2ap002: 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/20211008092656.421-3-caihuoqing@baidu.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/gp2ap002.c

@@ -503,12 +503,9 @@ static int gp2ap002_probe(struct i2c_client *client,
 	if (!gp2ap002->is_gp2ap002s00f) {
 		gp2ap002->alsout = devm_iio_channel_get(dev, "alsout");
 		if (IS_ERR(gp2ap002->alsout)) {
-			if (PTR_ERR(gp2ap002->alsout) == -ENODEV) {
-				dev_err(dev, "no ADC, deferring...\n");
-				return -EPROBE_DEFER;
-			}
-			dev_err(dev, "failed to get ALSOUT ADC channel\n");
-			return PTR_ERR(gp2ap002->alsout);
+			ret = PTR_ERR(gp2ap002->alsout);
+			ret = (ret == -ENODEV) ? -EPROBE_DEFER : ret;
+			return dev_err_probe(dev, ret, "failed to get ALSOUT ADC channel\n");
 		}
 		ret = iio_get_channel_type(gp2ap002->alsout, &ch_type);
 		if (ret < 0)
@@ -521,15 +518,14 @@ static int gp2ap002_probe(struct i2c_client *client,
 	}
 
 	gp2ap002->vdd = devm_regulator_get(dev, "vdd");
-	if (IS_ERR(gp2ap002->vdd)) {
-		dev_err(dev, "failed to get VDD regulator\n");
-		return PTR_ERR(gp2ap002->vdd);
-	}
+	if (IS_ERR(gp2ap002->vdd))
+		return dev_err_probe(dev, PTR_ERR(gp2ap002->vdd),
+				     "failed to get VDD regulator\n");
+
 	gp2ap002->vio = devm_regulator_get(dev, "vio");
-	if (IS_ERR(gp2ap002->vio)) {
-		dev_err(dev, "failed to get VIO regulator\n");
-		return PTR_ERR(gp2ap002->vio);
-	}
+	if (IS_ERR(gp2ap002->vio))
+		return dev_err_probe(dev, PTR_ERR(gp2ap002->vio),
+				     "failed to get VIO regulator\n");
 
 	/* Operating voltage 2.4V .. 3.6V according to datasheet */
 	ret = regulator_set_voltage(gp2ap002->vdd, 2400000, 3600000);