sfc: support TC rules which require OR-AR-CT-AR flow

sfc: support TC rules which require OR-AR-CT-AR flow

When a foreign LHS rule (TC rule from a tunnel netdev which requests
 conntrack lookup) matches on inner headers or enc_key_id, these matches
 cannot be performed by the Outer Rule table, as the keys are only
 available after the tunnel type has been identified (by the OR lookup)
 and the rest of the headers parsed accordingly.
Offload such rules with an Action Rule, using the LOOKUP_CONTROL section
 of the AR response to specify the conntrack and/or recirculation actions,
 combined with an Outer Rule which performs only the usual Encap Match
 duties.
This processing flow, as it requires two AR lookups per packet, is less
 performant than OR-CT-AR, so only use it where necessary.

Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>