Removing unused VPP sessions by initializing only when used in order to help
reduce CPU utilization.

Thanks to Maxym for the guidance.
Signed-off-by: Joe Olivas <joseph.k.olivas@intel.com>
Signed-off-by: Maxym Dmytrychenko <maxim.d33@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>