iio: adc: ti-ads7950: 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/20211008092858.495-9-caihuoqing@baidu.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ti-ads7950.c

@@ -600,8 +600,8 @@ static int ti_ads7950_probe(struct spi_device *spi)
 
 	st->reg = devm_regulator_get(&spi->dev, "vref");
 	if (IS_ERR(st->reg)) {
-		dev_err(&spi->dev, "Failed to get regulator \"vref\"\n");
-		ret = PTR_ERR(st->reg);
+		ret = dev_err_probe(&spi->dev, PTR_ERR(st->reg),
+				     "Failed to get regulator \"vref\"\n");
 		goto error_destroy_mutex;
 	}