vswitches: Fix error in loading eventfd module

vswitches: Fix error in loading eventfd module

Load eventfd only when vhost-cuse is specified as
the guest access method.

This commit also includes quickstart update for executing PVP tests.

JIRA: VSPERF-59

Change-Id: I41f116ab1c42f704026567a269922c07994b15a5
Signed-off-by: Dino Simeon Madarang <dino.simeonx.madarang@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Billy O Mahony <billy.o.mahony@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Gurpreet Singh <gurpreet.singh@spirent.com>
Reviewed-by: Tv Rao <tv.rao@freescale.com>
Reviewed-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>