In the case where a hardware error is detected during
ioat_process_events, hardware may advance (by one descriptor, probably)
and a subsequent ioat_process_events may race the intended ioat_reset_hw
followup. In that case, the second process_events would observe a
completion update that does not match the software "last_seen" status,
and attempt to successfully complete already-failed descriptors.
Guard against this race with the resetting_cleanup flag.
Reviewed by: bdrewery, markj
Sponsored by: Dell EMC Isilon
3a37091931