iwlwifi: mvm: remove DQA non-STA client mode special case

iwlwifi: mvm: remove DQA non-STA client mode special case

When we get a non-STA frame to transmit in client mode, we try to use
the IWL_MVM_DQA_BSS_CLIENT_QUEUE queue (queue #4). However, at this
point, the queue might not be allocated at all, causing warnings. The
scenario on which this happened was a race condition between mac80211
and our queue allocation work:
 * mac80211 sends auth
 * we stop mac80211 queues to allocate a hw queue
 * authentication is aborted
 * we allocate HW queue and start mac80211 queues
 * mac80211 removes station
 * mac80211 hands us the auth frame from the pending queue

At this point, since mac80211 has already removed the station, we try
to transmit the frame through this special non-station case on queue
4 anyway.

In order to really use it properly, we'd have to again go through the
hw queue allocation work, and attach it to a station, etc. In this
case that isn't possible (there's no station anymore), but if this
special case were needed, then we'd have to do it this way.

However, the special case is documented to exist for TDLS, but can't
trigger there because the TDLS setup frames etc. are normal to-DS
frames going to the peer through the AP. Testing also confirms that
this code path isn't triggered in TDLS.

Therefore, remove the code path to avoid using an unused queue. The
erroneous frame described above will still be transmitted on the AUX
queue, but arguably that's a mac80211 problem, which will eventually
be fixed by moving everything there to TXQs.

Fixes: e3118ad74d7e ("iwlwifi: mvm: support tdls in dqa mode")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>