Previously, openvswitch was only started when we were using the ODL
provider but we should start it for all providers that need it. As such
we move the conditional which checks whether Open vSwitch is needed into
a new variable and we use that to start/enable the service and also to
install the package when needed.
Change-Id: I4ec4fc2c2124a941f24478cbdf39ed34c0dce56f