mlxsw: core_acl_flex_actions: Implement flow_offload action cookie offload

Track cookies coming down to driver by flow_offload.
Assign a cookie_index to each unique cookie binary. Use previously
defined "Trap with userdef" flex action to ask HW to pass cookie_index
alongside with the dropped packets.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>