So, if we're processing a timeout, and we've sent an ABORT to the firmware
for that timeout, but not yet received the response from the firmware, AND
we get another timeout, we queue the timeout and freeze the queue. However,
when we've finally processed them all, we only release the queue once. This
causes all I/O to halt as the devq remains frozen forever.
Instead, only freeze the queue when we start the process (eg set INRESET
on the target). This will allow the release when all the timed out I/Os have
finished ABORTing.