ath9k: Use bitfields for sc operations

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/rc.c b/drivers/net/wireless/ath9k/rc.c
index 73c460a..20e1084 100644
--- a/drivers/net/wireless/ath9k/rc.c
+++ b/drivers/net/wireless/ath9k/rc.c
@@ -1903,7 +1903,7 @@
 	int state;
 	DECLARE_MAC_BUF(mac);
 
-	if (!sc->sc_txaggr)
+	if (!(sc->sc_flags & SC_OP_TXAGGR))
 		return;
 
 	txtid = ATH_AN_2_TID(an, tidno);