md: remove/add redundancy group only in level change

del_gendisk is called in synchronous way now. So it doesn't need to handle
redundancy group in stop path separately.

Reviewed-by: Yu Kuai <[email protected]>
Signed-off-by: Xiao Ni <[email protected]>
Link: https://lore.kernel.org/linux-raid/[email protected]
Signed-off-by: Yu Kuai <[email protected]>

Author: XiaoNi87

drivers/md/md.c

@@ -6523,8 +6523,6 @@ static void __md_stop(struct mddev *mddev)
 	if (mddev->private)
 		pers->free(mddev, mddev->private);
 	mddev->private = NULL;
-	if (pers->sync_request && mddev->to_remove == NULL)
-		mddev->to_remove = &md_redundancy_group;
 	put_pers(pers);
 	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);