CVE-2026-80535: xfs: don't double-lock when deleting a self-referential directory

In the Linux kernel, the following vulnerability has been resolved:

xfs: don't double-lock when deleting a self-referential directory

LOLLM notices that the dirtree scrubber can detect a directory that refers to itself. In this case, it's not correct for the directory tree repair code to try to iolock/ilock both sc->ip and dp, because they're the same inode. Fix this by detecting that corner case and handling it appropriately.