[dpdk] Get back to shared memory model

[dpdk] Get back to shared memory model

The per port model potentially requires an increase in memory
resource requirements (which is limited by labs) to support the
same number of ports and configuration as the shared port model.

Set linux:network:openvswitch:per_port_memory explicitly to true
to enable per port mempools support for DPDK devices.

Change-Id: I130885afc50e7a047f8835113d370840827ad718
Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>