This patch addresses changes made by usage of new symbols
like unregister_netdevice_queue() which are not possible to backport
due to their reliance on internal symbols on net/core/dev.c

The patch that introduced this on mac80211 was:

    mac80211: Speedup ieee80211_remove_interfaces()
    
    Speedup ieee80211_remove_interfaces() by factorizing synchronize_rcu() calls
    
    Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
    Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
    Signed-off-by: John W. Linville <linville@tuxdriver.com>

--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1589,6 +1589,7 @@ void ieee80211_sdata_stop(struct ieee802
  * Remove all interfaces, may only be called at hardware unregistration
  * time because it doesn't do RCU-safe list removals.
  */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,33))
 void ieee80211_remove_interfaces(struct ieee80211_local *local)
 {
 	struct ieee80211_sub_if_data *sdata, *tmp;
@@ -1616,6 +1617,22 @@ void ieee80211_remove_interfaces(struct
 		kfree(sdata);
 	}
 }
+#else
+void ieee80211_remove_interfaces(struct ieee80211_local *local)
+{
+	struct ieee80211_sub_if_data *sdata, *tmp;
+
+	ASSERT_RTNL();
+
+	list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) {
+		mutex_lock(&local->iflist_mtx);
+		list_del(&sdata->list);
+		mutex_unlock(&local->iflist_mtx);
+
+		unregister_netdevice(sdata->dev);
+	}
+}
+#endif
 
 static int netdev_notify(struct notifier_block *nb,
 			 unsigned long state,
