sfc: functions to insert/remove conntrack entries to MAE hardware

Translate from software struct efx_tc_ct_entry objects to the key
 and response bitstrings, and implement insertion and removal of
 these entries from the hardware table.
Callers of these functions will be added in subsequent patches.

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>