hwmon: (adt7470) Return proper error code for adt7470_probe()

Signed-off-by: Axel Lin <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/adt7470.c

···
 	init_completion(&data->auto_update_stop);
 	data->auto_update = kthread_run(adt7470_update_thread, client,
 					dev_name(data->hwmon_dev));
-	if (IS_ERR(data->auto_update))
+	if (IS_ERR(data->auto_update)) {
+		err = PTR_ERR(data->auto_update);
 		goto exit_unregister;
+	}
 
 	return 0;