AZL-98112

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

igc: remove napisynchronize() in igcdown()

When an AFXDP zero-copy application is killed abruptly, the XSK pool is torn down but NAPI keeps polling. igccleanrxirqzc() then returns the full budget on every poll, so napicompletedone() never clears NAPISTATE_SCHED.

igcdown() calls napisynchronize() before napidisable(), so it spins forever waiting for that bit and the interface never goes down. Drop the napisynchronize() and let napidisable() do the job -- it sets NAPISTATEDISABLE, which forces the stuck poll to complete. Reorder it ahead of igcsetqueuenapi() so the NAPI mapping is cleared only after polling has stopped, matching the recent igb fix b1e067240379.