flow dpdk: introduce IP in IP support for flow

flow dpdk: introduce IP in IP support for flow

This patch introduces IP in IP packet support for flow cli and dpdk plugin.
Specifically, the following IP in IP packet types are supported:
	MAC-IPv4-IPv4-TCP/UDP/None,
	MAC-IPv4-IPv6-TCP/UDP/None,
	MAC-IPv6-IPv4-TCP/UDP/None,
	MAC-IPv6-IPv6-TCP/UDP/None,

IP in IP flow rules can be created by using the following new keywords in vppctl:
	in-src-ip, in-dst-ip        : to provide information for inner IPv4 header
	in-ip6-src-ip, in-ip6-dst-ip: to provide information for inner IPv6 header
	in-proto                    : to specify inner transport layer protocol type (TCP or UDP)
	in-src-port, in-dst-port    : to provide information for inner TCP/UDP header

An example to create flow rule for MAC-IPv6-IPv6-TCP:
	test flow add index 0 ip6-src-ip any ip6-dst-ip any in-ip6-src-ip any in-ip6-dst-ip any in-proto tcp in-src-port 1234 in-dst-port any rss function default

Another example to create flow rule for MAC-IPv6-IPv6:
	test flow add index 0 ip6-src-ip any in-ip6-src-ip any rss function default

Type: feature

Signed-off-by: Xinyao Cai <xinyao.cai@intel.com>
Change-Id: I6a1ca36d47eb65b9cb5a4b8d874b2a7f017c35cd