flow: add RSS support

flow: add RSS support

This patch enables the RSS configuration through vnet/flow interface
With this RSS feature, users can config the RSS functions for specific flows

Currently, it supports:
  default, toeplitz and symmetric_toeplitz rss function, and
  ipv4-tcp/ipv4-udp/ipv6-tcp/ipv6-ucp flow types

Users can use the following options to combine with above flow
types for more specific hash input set selection:
  l3-src-only, l3-dst-only, l4-src-only, l4-dst-only

Command line:
test flow add dst-ip any proto udp rss function default rss types ipv4-tcp use l3-dst-only
test flow add dst-ip any proto udp rss function toeplitz rss types ipv4-udp use l4-src-only
test flow add dst-ip any proto udp rss function symmetric_toeplitz rss types ipv6-udp use l3-src-only and l3-dst-only

Type: feature

Signed-off-by: Chenmin Sun <chenmin.sun@intel.com>
Change-Id: I213efc76dc8af37f2f63605884f353e05b0f5d2a