ath9k_hw: remove direct accesses to channel mode flags

Use wrappers where available. Simplifies code and helps with further
improvements to the channel data structure

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/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 62c93a6..563f8a9 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2023,8 +2023,7 @@
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath9k_channel *curchan = ah->curchan;
 
-	if ((ah->caps.hw_caps & ATH9K_HW_CAP_APM) &&
-	    (curchan->channelFlags & CHANNEL_5GHZ) &&
+	if ((ah->caps.hw_caps & ATH9K_HW_CAP_APM) && IS_CHAN_5GHZ(curchan) &&
 	    (chainmask == 0x7) && (rate < 0x90))
 		return 0x3;
 	else if (AR_SREV_9462(ah) && ath9k_hw_btcoex_is_enabled(ah) &&