PF_RING: clean-up old code

This removes old PF_RING API, and checks if the lib version is >= 6,
so oldest PF_RING version won't supported.

- PR build: https://buildbot.openinfosecfoundation.org/builders/glongo/builds/9
- PR pcaps: https://buildbot.openinfosecfoundation.org/builders/glongo-pcap/builds/9