netdev-dpdk: Check dpdk-extra when reading db

netdev-dpdk: Check dpdk-extra when reading db

A previous patch introduced the ability to pass arbitrary EAL command
line options via the dpdk_extras database entry. This commit enhances
that by warning the user when such a configuration is detected and
prefering the value in the database.

Suggested-by: Sean K Mooney <sean.k.mooney@intel.com>
Signed-off-by: Aaron Conole <aconole@redhat.com>
Tested-by: Sean K Mooney <sean.k.mooney@intel.com>
Tested-by: Kevin Traynor <kevin.traynor@intel.com>
Acked-by: Panu Matilainen <pmatilai@redhat.com>
Acked-by: Flavio Leitner <fbl@sysclose.org>
Acked-by: Daniele Di Proietto <diproiettod@vmware.com>