iwlwifi: mvm: support dqa queue sharing

iwlwifi: mvm: support dqa queue sharing

Support DQA queue sharing when no free queue exists for
allocation to a STA that already exists. This means that
a single queue will serve more than a single TID (although
the RA will be the same for all TIDs served).

We try to choose the lowest AC possible, to ensure the
shared queues have the lowest possible combined AC
requirements. The queue to share is chosen only from the
same RA's DATA queues as follows (in descending priority):
 1. An AC_BE queue
 2. Same AC queue
 3. Highest AC queue that is lower than new AC
 4. Any existing AC (there always is at least 1 DATA queue)

If any aggregations existed for any of the TIDs of the
shared queue - they are stopped (the FW is notified), but
no delBA is sent.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>