Ensures that the configuration of a VF is not overwritten in Zookeeper
on a node restart. The SRIOVVFInstance handlers were modified to start
with None values, so that the DataWatch statements will always trigger
updates to the live system interfaces on daemon startup, thus ensuring
that the config stored in Zookeeper is applied to the system on startup
(mostly relevant after a cold boot or if the API changes them during a
daemon restart).