DPDK: fix high pkt drop for 16 lcores
DPDK: fix high pkt drop for 16 lcores

I have no hardware with 16 cores, but I guess with lots
of lcores assigned to vRouter/DPDK some of them might get
sleep due to no RX queues assigned.

Change-Id: I7e37e14ef9aebfc3613ef5e908091ee35093d1bb
Closes-bug: #1505472

codilime/contrail-vrouter,codilime/contrail-vrouter,codilime/contrail-vrouter,codilime/contrail-vrouter