mac80211: fix Rx reordering with RX_FLAG_AMSDU_MORE

Some drivers (e.g. ath10k) report A-MSDU subframes
individually with identical seqno. The A-MPDU Rx
reorder code did not account for that which made
it practically unusable with drivers using
RX_FLAG_AMSDU_MORE because it would end up
dropping a lot of frames resulting in confusion in
upper network transport layers.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>