ath9k_htc: Move endpoint header parsing to TX tasklet

There is no need to do endpoint header removal in the ISR.
Also, this is needed when TX slot management is added later on.
Use a helper function to strip the driver header.

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index 356f49c..0831ca3 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -277,6 +277,7 @@
 struct ath9k_htc_tx_ctl {
 	u8 type; /* ATH9K_HTC_* */
 	u8 epid;
+	u8 txok;
 };
 
 static inline struct ath9k_htc_tx_ctl *HTC_SKB_CB(struct sk_buff *skb)