iwlwifi: mvm: respect disable Tx AGG parameter

We didn't check that we allowed to start Tx AGG. This can
possibly be avoided by a module parameter. Fix that.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/iwlwifi/mvm/mac80211.c

@@ -273,6 +273,10 @@ static int iwl_mvm_mac_ampdu_action(struct ieee80211_hw *hw,
 		ret = iwl_mvm_sta_rx_agg(mvm, sta, tid, 0, false);
 		break;
 	case IEEE80211_AMPDU_TX_START:
+		if (iwlwifi_mod_params.disable_11n & IWL_DISABLE_HT_TXAGG) {
+			ret = -EINVAL;
+			break;
+		}
 		ret = iwl_mvm_sta_tx_agg_start(mvm, vif, sta, tid, ssn);
 		break;
 	case IEEE80211_AMPDU_TX_STOP_CONT: