iio: adc: ad7192: Simplify using devm_regulator_get_enable()

Use devm_regulator_get_enable() instead of open coded get, enable,
add-action-to-disable-at-detach - pattern. Also drop the seemingly unused
struct member 'dvdd'.

Signed-off-by: Matti Vaittinen <[e-mail]>
Link: https://lore.kernel.org/r/9719c4[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/ad7192.c

···
 struct ad7192_state {
 	const struct ad7192_chip_info	*chip_info;
 	struct regulator		*avdd;
-	struct regulator		*dvdd;
 	struct clk			*mclk;
 	u16				int_vref_mv;
 	u32				fclk;
···
 	if (ret)
 		return ret;
 
-	st->dvdd = devm_regulator_get(&spi->dev, "dvdd");
-	if (IS_ERR(st->dvdd))
-		return PTR_ERR(st->dvdd);
-
-	ret = regulator_enable(st->dvdd);
-	if (ret) {
-		dev_err(&spi->dev, "Failed to enable specified DVdd supply\n");
-		return ret;
-	}
-
-	ret = devm_add_action_or_reset(&spi->dev, ad7192_reg_disable, st->dvdd);
+	ret = devm_regulator_get_enable(&spi->dev, "dvdd");
 	if (ret)
-		return ret;
+		return dev_err_probe(&spi->dev, ret, "Failed to enable specified DVdd supply\n");
 
 	ret = regulator_get_voltage(st->avdd);
 	if (ret < 0) {