New firmware and firmware (qca6174 hw3.0+ and fw
266+) are capable of full aggregation rx
reordering. If it's enabled then Rx is handled via
a new, separate htt event.

The rx ring behaviour is changed a little to
support the new rx scheme. These changes shouldn't
affect qca988x performance.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>