staging: iio: impedance-analyzer: ad5933: Use devm_regulator_get_enable_read_voltage()

We can reduce boilerplate code by using
devm_regulator_get_enable_read_voltage().
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20240429-regulator-get-enable-get-votlage-v2-6-b1f11ab766c1@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/staging/iio/impedance-analyzer/ad5933.c

@@ -84,7 +84,6 @@
 
 struct ad5933_state {
 	struct i2c_client		*client;
-	struct regulator		*reg;
 	struct clk			*mclk;
 	struct delayed_work		work;
 	struct mutex			lock; /* Protect sensor state */
@@ -660,13 +659,6 @@ static void ad5933_work(struct work_struct *work)
 	}
 }
 
-static void ad5933_reg_disable(void *data)
-{
-	struct ad5933_state *st = data;
-
-	regulator_disable(st->reg);
-}
-
 static int ad5933_probe(struct i2c_client *client)
 {
 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
@@ -685,23 +677,9 @@ static int ad5933_probe(struct i2c_client *client)
 
 	mutex_init(&st->lock);
 
-	st->reg = devm_regulator_get(&client->dev, "vdd");
-	if (IS_ERR(st->reg))
-		return PTR_ERR(st->reg);
-
-	ret = regulator_enable(st->reg);
-	if (ret) {
-		dev_err(&client->dev, "Failed to enable specified VDD supply\n");
-		return ret;
-	}
-
-	ret = devm_add_action_or_reset(&client->dev, ad5933_reg_disable, st);
-	if (ret)
-		return ret;
-
-	ret = regulator_get_voltage(st->reg);
+	ret = devm_regulator_get_enable_read_voltage(&client->dev, "vdd");
 	if (ret < 0)
-		return ret;
+		return dev_err_probe(&client->dev, ret, "failed to get vdd voltage\n");
 
 	st->vref_mv = ret / 1000;