CVE-2026-80553: s390/vfio_ccw: Cancel existing workqueues

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

s390/vfioccw: Cancel existing workqueues

The initialization of the iowork and crwwork workqueues begs the question of whether they should be un-initialized. Add the corresponding cleanup tags in releasedev to ensure work isn't dispatched after the private struct is free'd.