iommufd: Fix missing update of domains_itree after splitting iopt_area

In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix missing update of domains_itree after splitting iopt_area In iopt_area_split(), if the original iopt_area has filled a domain and is linked to domains_itree, pages_nodes have to be properly reinserted. Otherwise the domains_itree becomes corrupted and we will UAF.