netdev-dpdk: Autofill lcore coremask if absent

netdev-dpdk: Autofill lcore coremask if absent

The user has control over the DPDK internal lcore coremask, but this
parameter can be autofilled with a bit more intelligence. If the user
does not fill this parameter in, we use the lowest set bit in the
current task CPU affinity. Otherwise, we will reassign the current
thread to the specified lcore mask, in addition to the dpdk lcore
threads.

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