Map the non-QoS TID to the voice queue, in order to ensure important
things like EAPOL frames make it out.

After a whole bunch of hacking/testing, I discovered that they weren't
being early-dropped by the stack (but I should look at ensuring that
later..) but were even making to the hardware transmit queue.
They were mostly even being received by the remote end.  However, the
remote end was completely ignoring them.

This didn't happen under 150-170MBit TCP tests as I'm guessing the TX
queue stayed very busy and the STA didn't do any scanning. However, when
doing 100Mbit/s of TCP traffic, the STA would do background scanning -
which involves it coming in and out of powersave mode with the AP.

Now, this is a total and utter hack around the real problems, which are:

* I need to implement proper power save handling and integrate it into
  the filtered frames support, so the driver/stack doesn't send frames
  whilst the station is actually in sleep;

* .. but frames were actually making it to the STA (macbook pro) and
  the AP did receive an ACK; but a tcpdump on the receiving side showed
  the EAPOL frame never made it. So the stack was dropping it for
  some reason;

* Importantly - the EAPOL frames are currently going into the non-QoS
  TID, which maps to the BE queue and is susceptible to that queue being
  busy doing other things, but;

* There's other traffic going on in the non-QoS TID from other contexts
  when scanning is going on and it's possible there's some races causing
  sequence number/IV issues, but;

* Importantly importantlly, I think the interaction with TID 16 multicast
  traffic in power save mode is causing issues - since I -believe- the
  sequence number space being used by the EAPOL frames on TID 16 overlaps
  with the multicast frames that have sequence numbers allocated and
  are then stuffed on the cabq.  Since with EAPOL frames being in TID 16
  and queued to the BE queue, it's going to be waiting to be serviced
  with all of the aggregate traffic going on - and if the CABQ gets
  emptied beforehand, those TID 16 multicast frames with sequence numbers
  will go out beforehand.

Now, there's quite likely a bunch of "stuff happening slightly out of
sequence" going on due to the nature of the TX path (read: lots of
overlapping and concurrent ath_start() and ath_raw_xmit() calls going
on, sigh) but I thought I had caught them all and stuffed each TID TX
behind a lock (that lasted as long as it needed to in order to get
the frame onto the relevant destination queue - thus keeping things
in order.)

Unfortunately the last problem is the big one and I'm going to stare at
it some more.  If it _is_

So this is a work around for now to ensure that EAPOL frames actually
make it out before any other stuff in the non-QoS TID and HOPEFULLY
before the CABQ gets active.

I'm now going to spend a little time in the TX path figuring out exactly
why the sender is rejecting things. There's two (well, three if you count
EAPOL contents invalid) possibilities:

* The sequence number is out of order (ie, something else like the multicast
  traffic on CABQ) is going out first on TID 16;
* The CCMP IV is out of order (similar to above - but less likely,  as the
  TX key for multicast traffic is different to unicast traffic);
* EAPOL contents strangely invalid.

AP: Ubiquiti RSPRO, AR9160/AR9220 NICs
STA: Macbook Pro, Broadcom 11n NIC