iio: adc: ad799x: fix probe error handling

BugLink: https://bugs.launchpad.net/bugs/1848780

commit c62dd449 upstream.

Since commit 0f7ddcc1 ("iio:adc:ad799x: Write default config on probe
and reset alert status on probe") the error path is wrong since it
leaves the vref regulator on. Fix this by disabling both regulators.

Fixes: 0f7ddcc1 ("iio:adc:ad799x: Write default config on probe and reset alert status on probe")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/iio/adc/ad799x.c

@@ -822,10 +822,10 @@ static int ad799x_probe(struct i2c_client *client,
 
 	ret = ad799x_write_config(st, st->chip_config->default_config);
 	if (ret < 0)
-		goto error_disable_reg;
+		goto error_disable_vref;
 	ret = ad799x_read_config(st);
 	if (ret < 0)
-		goto error_disable_reg;
+		goto error_disable_vref;
 	st->config = ret;
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,