regulator: core: Always use return value when regulator_dev_lookup() fails

Ensure that the return value is always set when we return now that the
logic has changed for regulator_get_optional() so we don't get missing
codes leaking out.

Reported-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/regulator/core.c

@@ -1263,12 +1263,13 @@ static struct regulator *_regulator_get(struct device *dev, const char *id,
 	if (rdev)
 		goto found;
 
+	regulator = ERR_PTR(ret);
+
 	/*
 	 * If we have return value from dev_lookup fail, we do not expect to
 	 * succeed, so, quit with appropriate error value
 	 */
 	if (ret && ret != -ENODEV) {
-		regulator = ERR_PTR(ret);
 		goto out;
 	}