iwlwifi: mvm: use helpers to get iwl_mvm_sta

Getting the mvm station out of station id requires dereferencing
the station id to get ieee80211_sta, then checking for pointer
validity and only then extract mvm station out.
Given that there are helpers to do it - use them instead of
duplicating the code whenever we need only mvm station.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
index 2ba1369..6f91c5b 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
@@ -1210,7 +1210,6 @@
 					struct iwl_d0i3_iter_data *iter_data)
 {
 	struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
-	struct ieee80211_sta *ap_sta;
 	struct iwl_mvm_sta *mvmsta;
 	u32 available_tids = 0;
 	u8 tid;
@@ -1219,11 +1218,10 @@
 		    mvmvif->ap_sta_id == IWL_MVM_STATION_COUNT))
 		return false;
 
-	ap_sta = rcu_dereference(mvm->fw_id_to_mac_id[mvmvif->ap_sta_id]);
-	if (IS_ERR_OR_NULL(ap_sta))
+	mvmsta = iwl_mvm_sta_from_staid_rcu(mvm, mvmvif->ap_sta_id);
+	if (!mvmsta)
 		return false;
 
-	mvmsta = iwl_mvm_sta_from_mac80211(ap_sta);
 	spin_lock_bh(&mvmsta->lock);
 	for (tid = 0; tid < IWL_MAX_TID_COUNT; tid++) {
 		struct iwl_mvm_tid_data *tid_data = &mvmsta->tid_data[tid];