Give Suricata priority to receive packets over Linux with mPIPE.

When installing the rules to tell mPIPE to send packet to Suricata,
give Suricata a higher priority than the default priority used by Linux. This way if
Linux also tells mPIPE to send it packets, Suricata will get them
instead, as long as Suricata is running.

https://buildbot.suricata-ids.org/builders/ken-tilera/builds/42