mt76: do not set status->aggr for NULL data frames

Avoids data connection stalls when the client toggles powersave mode

Fixes: aee5b8cf2477 ("mt76: implement A-MPDU rx reordering in the driver code")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt76/mt76x2_mac.c

@@ -341,7 +341,7 @@ int mt76x2_mac_process_rx(struct mt76x2_dev *dev, struct sk_buff *skb,
 
 	mt76x2_remove_hdr_pad(skb, pad_len);
 
-	if (rxinfo & MT_RXINFO_BA)
+	if ((rxinfo & MT_RXINFO_BA) && !(rxinfo & MT_RXINFO_NULL))
 		status->aggr = true;
 
 	if (WARN_ON_ONCE(len > skb->len))