The TC extra channel will need its own special RX handling, which must
 operate before any code that expects the RX buffer to contain a network
 packet; buffers on this RX queue contain MAE counter packets in a
 special format that does not resemble an Ethernet frame, and many fields
 of the RX packet prefix are not populated.
The USER_MARK field, however, is populated with the generation count from
 the counter subsystem, which needs to be passed on to the RX handler.
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>