app/testpmd: support integrity flow item

The integrity item allows the application to match
on the integrity of a packet.

Usage example:
match that packet integrity checks are OK. The checks depend on
packet layers. For example ICMP packet will not check L4 level.
flow create 0 ingress pattern integrity value mask 0x01 value spec 0x01

Match that L4 packet is OK - check L2 & L3 & L4 layers:
flow create 0 ingress pattern integrity value mask 0xfe value spec 0xfe

Signed-off-by: Ori Kam <orika@nvidia.com>
Signed-off-by: Gregory Etelson <getelson@nvidia.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>