CVE-2026-99080: fs: Free any excess xarray nodes in clear_inode()

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

fs: Free any excess xarray nodes in clearinode()

For many years we've had a hard to hit leak of xarray nodes. Hugh documented it well in commit 786b31121a2c. Recently people and syzbot have found ways to force it to happen with madvise. Rather than fix the leaks where they happen, just call xadestroy() which has the side-effect of cycling the ipages lock.