sfc: add MAE table machinery for conntrack table

Access to the connection tracking table in EF100 hardware is through
 a "generic" table mechanism, whereby a firmware call at probe time
 gives the driver a description of the field widths and offsets, so
 that the driver can then construct key and response bitstrings at
 runtime.
Probe the NIC for this information and populate the needed metadata
 into a new meta_ct field of struct efx_tc_state.

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