ath9k: make ath_ant_div_conf_fast_divbias static

  CHECK   drivers/net/wireless/ath/ath9k/recv.c
drivers/net/wireless/ath/ath9k/recv.c:1341:6: warning: symbol 'ath_ant_div_conf_fast_divbias' was not declared. Should it be static?
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -1338,7 +1338,7 @@ static void ath_select_ant_div_from_quick_scan(struct ath_ant_comb *antcomb,
 	}
 }
 
-void ath_ant_div_conf_fast_divbias(struct ath_hw_antcomb_conf *ant_conf)
+static void ath_ant_div_conf_fast_divbias(struct ath_hw_antcomb_conf *ant_conf)
 {
 	/* Adjust the fast_div_bias based on main and alt lna conf */
 	switch ((ant_conf->main_lna_conf << 4) | ant_conf->alt_lna_conf) {