staging: iio/ad7291: fix error code in ad7291_probe()

We should be returning a negative error code instead of success here.

This would have been detected by GCC, except that the "ret" variable was
initialized with a bogus value to disable GCC's uninitialized variable
warnings.  I've cleaned that up, as well.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: Stable@vger.kernel.org

drivers/staging/iio/adc/ad7291.c

@@ -465,7 +465,7 @@ static int ad7291_probe(struct i2c_client *client,
 	struct ad7291_platform_data *pdata = client->dev.platform_data;
 	struct ad7291_chip_info *chip;
 	struct iio_dev *indio_dev;
-	int ret = 0;
+	int ret;
 
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
 	if (!indio_dev)
@@ -475,7 +475,7 @@ static int ad7291_probe(struct i2c_client *client,
 	if (pdata && pdata->use_external_ref) {
 		chip->reg = devm_regulator_get(&client->dev, "vref");
 		if (IS_ERR(chip->reg))
-			return ret;
+			return PTR_ERR(chip->reg);
 
 		ret = regulator_enable(chip->reg);
 		if (ret)