ath9k: Free Beacon skbs in AP mode

Fix a memory leak where AP mode did not free transmitted Beacon frame
skbs.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Acked-by: Pat Erley <pat-lkml@erley.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath9k/beacon.c

@@ -167,6 +167,7 @@ static struct ath_buf *ath_beacon_generate(struct ath_softc *sc, int if_id)
 		pci_unmap_single(sc->pdev, bf->bf_dmacontext,
 				 skb->len,
 				 PCI_DMA_TODEVICE);
+		dev_kfree_skb_any(skb);
 	}
 
 	skb = ieee80211_beacon_get(sc->hw, vif);