net/enic: enable flow API for VF representor

net/enic: enable flow API for VF representor

Use Flow Manager (flowman) to support flow API for
representors. Representor's flow handlers simply invoke PF handlers
and pass the representor's flowman structure. The PF flowman handlers
are aware of representors and perform appropriate devcmds to create
flows on the NIC.

Also use flowman to create internal flows for implicit VF-representor
path. With that, representor Tx/Rx is now functional.

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