iio: chemical: mhz19b: Fix error code in probe()

Return -ENOMEM if devm_iio_device_alloc() fails. Don't return success.

Fixes: 4572a70b3681 ("iio: chemical: Add support for Winsen MHZ19B CO2 sensor")
Signed-off-by: Dan Carpenter <[e-mail]>
Reviewed-by: David Lechner <[e-mail]>
Acked-by: Gyeyoung Baek <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/chemical/mhz19b.c

···
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
 	if (!indio_dev)
-		return ret;
+		return -ENOMEM;
 	serdev_device_set_drvdata(serdev, indio_dev);
 
 	st = iio_priv(indio_dev);