ath9k: don't use BAW tracking on PS responses for non-AMPDU packets

When .release_buffered_frames was implemented, only A-MPDU packets were
buffered internally. Now that this has changed, the BUF_AMPDU flag needs
to be checked before calling ath_tx_addto_baw
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/xmit.c

@@ -1556,8 +1556,10 @@ void ath9k_release_buffered_frames(struct ieee80211_hw *hw,
 			__skb_unlink(bf->bf_mpdu, tid_q);
 			list_add_tail(&bf->list, &bf_q);
 			ath_set_rates(tid->an->vif, tid->an->sta, bf);
+			if (bf_isampdu(bf)) {
 				ath_tx_addto_baw(sc, tid, bf);
 				bf->bf_state.bf_type &= ~BUF_AGGR;
+			}
 			if (bf_tail)
 				bf_tail->bf_next = bf;