mt76: mt7915: do not do any work in napi poll after calling napi_complete_done()

Fixes a race condition where multiple tx cleanup or sta poll tasks could run
in parallel.
Signed-off-by: NFelix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/dma.c

@@ -95,16 +95,13 @@ static int mt7915_poll_tx(struct napi_struct *napi, int budget)
 	dev = container_of(napi, struct mt7915_dev, mt76.tx_napi);
 
 	mt7915_tx_cleanup(dev);
-
-	if (napi_complete_done(napi, 0))
-		mt7915_irq_enable(dev, MT_INT_TX_DONE_ALL);
-
-	mt7915_tx_cleanup(dev);
-
 	mt7915_mac_sta_poll(dev);
 
 	tasklet_schedule(&dev->mt76.tx_tasklet);
 
+	if (napi_complete_done(napi, 0))
+		mt7915_irq_enable(dev, MT_INT_TX_DONE_ALL);
+
 	return 0;
 }