iio: adc: stm32: Fix missing return in booster error path

Conversion of error paths to dev_err_probe() dropped one return
statement.  The driver will continue to probe if getting booster
regulator fails.

Fixes: ce30eeb6 ("iio: adc: stm32: Simplify with dev_err_probe()")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/1599727927-7776-1-git-send-email-krzk@kernel.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stm32-adc-core.c

@@ -595,7 +595,7 @@ static int stm32_adc_core_switches_probe(struct device *dev,
 		if (IS_ERR(priv->booster)) {
 			ret = PTR_ERR(priv->booster);
 			if (ret != -ENODEV)
-				dev_err_probe(dev, ret, "can't get booster\n");
+				return dev_err_probe(dev, ret, "can't get booster\n");
 
 			priv->booster = NULL;
 		}