ath9k/ath10k: remove unnecessary channel_switch_beacon callbacks

The channel_switch_beacon callback is optional, so it doesn't have to
be defined if it's not going to do anything useful with it.  Both
ath9k and ath10k define the callback and just returns.  This commit
removes them.

Cc: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/mac.c

@@ -4211,14 +4211,6 @@ static int ath10k_set_bitrate_mask(struct ieee80211_hw *hw,
 					   fixed_nss, force_sgi);
 }
 
-static void ath10k_channel_switch_beacon(struct ieee80211_hw *hw,
-					 struct ieee80211_vif *vif,
-					 struct cfg80211_chan_def *chandef)
-{
-	/* there's no need to do anything here. vif->csa_active is enough */
-	return;
-}
-
 static void ath10k_sta_rc_update(struct ieee80211_hw *hw,
 				 struct ieee80211_vif *vif,
 				 struct ieee80211_sta *sta,
@@ -4327,7 +4319,6 @@ static const struct ieee80211_ops ath10k_ops = {
 	.restart_complete		= ath10k_restart_complete,
 	.get_survey			= ath10k_get_survey,
 	.set_bitrate_mask		= ath10k_set_bitrate_mask,
-	.channel_switch_beacon		= ath10k_channel_switch_beacon,
 	.sta_rc_update			= ath10k_sta_rc_update,
 	.get_tsf			= ath10k_get_tsf,
 #ifdef CONFIG_PM