ath9k: fix SC_OP_INVALID test in ath9k_tx99_init()

SC_OP_INVALID is zero so the test is always false.  We're supposed to be
testing the lowest bit instead.

Fixes: 89f927af7f33 ('ath9k: add TX99 support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/tx99.c

@@ -99,7 +99,7 @@ static int ath9k_tx99_init(struct ath_softc *sc)
 	struct ath_tx_control txctl;
 	int r;
 
-	if (sc->sc_flags & SC_OP_INVALID) {
+	if (test_bit(SC_OP_INVALID, &sc->sc_flags)) {
 		ath_err(common,
 			"driver is in invalid state unable to use TX99");
 		return -EINVAL;