net/enic: add flow implementation based on Flow Manager API

net/enic: add flow implementation based on Flow Manager API

Flow Manager API is the new firmware interface that exposes match
action capabilities in 1400 series VIC adapters. It is intended for
virtual switch offloads and enables more advanced features than the
existing filter API. For example, it supports VXLAN encap and decap
actions, and exposes TCAM and exact match tables.

Add the new flow implementation using Flow Manager and use it when
available. When Flow Manager is not available, the driver will
continue to use the old filter-based flow implementation.

Signed-off-by: John Daley <johndale@cisco.com>
Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>