btrfs: delayed-inode: drop pointless BUG_ON in __btrfs_remove_delayed_item()

There's a BUG_ON checking for a valid pointer of fs_info::delayed_root
but it is valid since init_mount_fs_info() and has the same lifetime as
fs_info.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delayed-inode.c

@@ -430,8 +430,6 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
 
 	delayed_root = delayed_node->root->fs_info->delayed_root;
 
-	BUG_ON(!delayed_root);
-
 	if (delayed_item->type == BTRFS_DELAYED_INSERTION_ITEM)
 		root = &delayed_node->ins_root;
 	else