rtlwifi: remove redundant pointer tid_data

tid_data is assigned but never read, hence it is redundant
and can be removed. Cleans up clang warning:

drivers/net/wireless/realtek/rtlwifi/base.c:1581:2: warning: Value
stored to 'tid_data' is never read
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/base.c

@@ -1630,7 +1630,6 @@ int rtl_tx_agg_stop(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		    struct ieee80211_sta *sta, u16 tid)
 {
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
-	struct rtl_tid_data *tid_data;
 	struct rtl_sta_info *sta_entry = NULL;
 
 	if (sta == NULL)
@@ -1643,7 +1642,6 @@ int rtl_tx_agg_stop(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		return -EINVAL;
 
 	sta_entry = (struct rtl_sta_info *)sta->drv_priv;
-	tid_data = &sta_entry->tids[tid];
 	sta_entry->tids[tid].agg.agg_state = RTL_AGG_STOP;
 
 	ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);