ath9k: Use atomic operations

The 'sc_flags' variable is being used in a number of places
with no locking whatsoever. This patch converts the usage
of sc_flags to atomic ops.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/debug.c b/drivers/net/wireless/ath/ath9k/debug.c
index c134dda..2831258 100644
--- a/drivers/net/wireless/ath/ath9k/debug.c
+++ b/drivers/net/wireless/ath/ath9k/debug.c
@@ -205,10 +205,10 @@
 	common->disable_ani = !!disable_ani;
 
 	if (disable_ani) {
-		sc->sc_flags &= ~SC_OP_ANI_RUN;
+		clear_bit(SC_OP_ANI_RUN, &sc->sc_flags);
 		del_timer_sync(&common->ani.timer);
 	} else {
-		sc->sc_flags |= SC_OP_ANI_RUN;
+		set_bit(SC_OP_ANI_RUN, &sc->sc_flags);
 		ath_start_ani(common);
 	}
 
@@ -1321,7 +1321,7 @@
 	u8 chainmask = (ah->rxchainmask << 3) | ah->rxchainmask;
 	u8 nread;
 
-	if (sc->sc_flags & SC_OP_INVALID)
+	if (test_bit(SC_OP_INVALID, &sc->sc_flags))
 		return -EAGAIN;
 
 	buf = vmalloc(size);