wifi: iwlwifi: mvm: make flush code a bit clearer

The mask building here is only relevant for the old TX API,
so move it into the else branch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230305124407.c0795543f254.I302124a8584dd049577b0c2c74ecd7c48ddf4f3e@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

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

@@ -5058,9 +5058,10 @@ static void iwl_mvm_mac_flush(struct ieee80211_hw *hw,
 			if (iwl_mvm_flush_sta(mvm, mvmsta, false))
 				IWL_ERR(mvm, "flush request fail\n");
 		} else {
-			msk |= mvmsta->tfd_queue_msk;
 			if (iwl_mvm_has_new_tx_api(mvm))
 				iwl_mvm_wait_sta_queues_empty(mvm, mvmsta);
+			else /* only used for !iwl_mvm_has_new_tx_api() below */
+				msk |= mvmsta->tfd_queue_msk;
 		}
 	}