iwlwifi: move agn only tx functions from iwlcore to iwlagn

Identify the tx functions only used by agn driver and move those from
iwlcore to iwlagn.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-sta.c b/drivers/net/wireless/iwlwifi/iwl-sta.c
index d401b6f..9c28ad7 100644
--- a/drivers/net/wireless/iwlwifi/iwl-sta.c
+++ b/drivers/net/wireless/iwlwifi/iwl-sta.c
@@ -1395,6 +1395,7 @@
 
 	iwl_send_add_sta(priv, &priv->stations[sta_id].sta, CMD_ASYNC);
 }
+EXPORT_SYMBOL(iwl_sta_modify_sleep_tx_count);
 
 int iwl_mac_sta_remove(struct ieee80211_hw *hw,
 			       struct ieee80211_vif *vif,