conf: Fix default VPP configuration

conf: Fix default VPP configuration

Number of VPP workers (aka PMD threads) was not specified
explicitly in default configuration file. Configuration
has been fixed to use the same cores as OVS with DPDK.

Change-Id: Icd3e5d6f429435fbc1ff580891f4b182d1c48729
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
Reviewed-by: Trevor Cooper <trevor.cooper@intel.com>