ACPI: video: improve PM notifer callback

PM notifier callbacks should check for supported events rather than filter
out the unsupported events. So that it won't break when a new event is
introduced.

No functional change in this patch.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_video.c

@@ -1707,12 +1707,9 @@ static int acpi_video_resume(struct notifier_block *nb,
 	int i;
 
 	switch (val) {
-	case PM_HIBERNATION_PREPARE:
-	case PM_SUSPEND_PREPARE:
-	case PM_RESTORE_PREPARE:
-		return NOTIFY_DONE;
-	}
-
+	case PM_POST_HIBERNATION:
+	case PM_POST_SUSPEND:
+	case PM_POST_RESTORE:
 		video = container_of(nb, struct acpi_video_bus, pm_nb);
 
 		dev_info(&video->device->dev, "Restoring backlight state\n");
@@ -1725,6 +1722,8 @@ static int acpi_video_resume(struct notifier_block *nb,
 		}
 
 		return NOTIFY_OK;
+	}
+	return NOTIFY_DONE;
 }
 
 static acpi_status