mt76: clear skb pointers from rx aggregation reorder buffer during cleanup

During the cleanup of the aggregation session, a rx handler (or release timer)
on another CPU might still hold a pointer to the reorder buffer and could
attempt to release some packets.
Clearing pointers during cleanup avoids a theoretical use-after-free bug here.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/agg-rx.c

@@ -276,6 +276,7 @@ static void mt76_rx_aggr_shutdown(struct mt76_dev *dev, struct mt76_rx_tid *tid)
 		if (!skb)
 			continue;
 
+		tid->reorder_buf[i] = NULL;
 		tid->nframes--;
 		dev_kfree_skb(skb);
 	}