ath9k: make ath9k_cmn_update_ichannel static

Rework its wrapper function to make it more generic, using it as a
replacement for previous calls to ath9k_cmn_update_ichannel.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index 2306f57..9c145fa 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -802,7 +802,7 @@
 		chan = &sband->channels[i];
 		ah->curchan = &ah->channels[chan->hw_value];
 		cfg80211_chandef_create(&chandef, chan, NL80211_CHAN_HT20);
-		ath9k_cmn_update_ichannel(ah->curchan, &chandef);
+		ath9k_cmn_get_channel(sc->hw, ah, &chandef);
 		ath9k_hw_set_txpowerlimit(ah, MAX_RATE_POWER, true);
 	}
 }