In some parts of Madwifi, SKBs are dispatched from the VAP device to the physical...

In some parts of Madwifi, SKBs are dispatched from the VAP device to the physical device using Linux kernel queuing, which does not understand our node reference system, so node references are carefully cleaned up if the packet is dropped.
However, the netif_rx and vlan_hwaccel_receive_skb functions dispatch the SKB to the higher networking levels, out of our domain.

Therefore, handle node references as appropriate.

git-svn-id: http://madwifi-project.org/svn/madwifi/trunk@3708 0192ed92-7a03-0410-a25b-9323aeb14dbd