iavf: fix PTP use-after-free during reset

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

iavf: fix PTP use-after-free during reset

Commit 7c01dbfc8a1c5f ("iavf: periodically cache PHC time") introduced a

worker to cache PHC time, but failed to stop it during reset or disable.

This creates a race condition where `iavf_reset_task()` or

`iavf_disable_vf()` free adapter resources (AQ) while the worker is still

running. If the worker triggers `iavf_queue_ptp_cmd()` during teardown, it

accesses freed memory/locks, leading to a crash.

Fix this by calling `iavf_ptp_release()` before tearing down the adapter.

This ensures `ptp_clock_unregister()` synchronously cancels the worker and

cleans up the chardev before the backing resources are destroyed.