use os-svc-enable to enable openvswitch

Unkike RHEL/Fedora, Debian/Ubuntu OVS package is called
openvswitch-switch. os-svc-enable can use map-services to
deal with the problem.

This change requires patch I2748a9db7f8ee456698187a9646bc7cda2256fe7.

Change-Id: I6e3df30dc3a6918f3a949a7dac47289ede5c3d1f
Merge "use os-svc-enable to enable openvswitch"