[S390] cio: ccw_device_online_store return -EINVAL in case of missing driver

If no driver is attached to a device or the driver provides no
set_online/set_offline function, setting this device online/offline
via its sysfs online attribute will silently fail but return success.

This patch changes the behavior to return -EINVAL in those cases.

Signed-off-by: Sebastian Ott <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/cio/device.c

···
 		spin_lock_irq(cdev->ccwlock);
 		ccw_device_sched_todo(cdev, CDEV_TODO_UNREG_EVAL);
 		spin_unlock_irq(cdev->ccwlock);
-	} else if (cdev->online && cdev->drv && cdev->drv->set_offline)
+		return 0;
+	}
+	if (cdev->drv && cdev->drv->set_offline)
 		return ccw_device_set_offline(cdev);
-	return 0;
+	return -EINVAL;
 }
 
 static int online_store_recog_and_online(struct ccw_device *cdev)
···
 			return -EAGAIN;
 	}
 	if (cdev->drv && cdev->drv->set_online)
-		ccw_device_set_online(cdev);
-	return 0;
+		return ccw_device_set_online(cdev);
+	return -EINVAL;
 }
 
 static int online_store_handle_online(struct ccw_device *cdev, int force)