iwlagn: solve sparse warning

Remove local variable that was shadowing another one
sta_priv hasn't changed since the beginning of the function, so don't define
another pointer with the same name to the same variable

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -2711,12 +2711,9 @@ static int iwlagn_mac_ampdu_action(struct ieee80211_hw *hw,
 			ret = 0;
 		if (priv->cfg->ht_params &&
 		    priv->cfg->ht_params->use_rts_for_aggregation) {
-			struct iwl_station_priv *sta_priv =
-				(void *) sta->drv_priv;
 			/*
 			 * switch off RTS/CTS if it was previously enabled
 			 */
-
 			sta_priv->lq_sta.lq.general_params.flags &=
 				~LINK_QUAL_FLAGS_SET_STA_TLC_RTS_MSK;
 			iwl_send_lq_cmd(priv, iwl_rxon_ctx_from_vif(vif),