ath9k: remove unused ath_rc_isvalid_txmask()

Cc: Derek Smithies <derek@indranet.co.nz>
Cc: Chittajit Mitra <Chittajit.Mitra@Atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -454,13 +454,6 @@ static inline void ath_rc_set_valid_txmask(struct ath_rate_priv *ath_rc_priv,
 	ath_rc_priv->valid_rate_index[index] = valid_tx_rate ? 1 : 0;
 }
 
-static inline int ath_rc_isvalid_txmask(struct ath_rate_priv *ath_rc_priv,
-					u8 index)
-{
-	ASSERT(index <= ath_rc_priv->rate_table_size);
-	return ath_rc_priv->valid_rate_index[index];
-}
-
 static inline
 int ath_rc_get_nextvalid_txrate(const struct ath_rate_table *rate_table,
 				struct ath_rate_priv *ath_rc_priv,