Restart openvswitch-switch after installation

This minor change restarts openvswitch-switch after installation
as the openvswitch kernel module may not be present when that service
gets installed/started.  In that situation, subsequent ovs-vsctl
commands will hang.

Change-Id: Idb1c2442e313707ced70f0792f6cc22c5fc7ef39
Closes-Bug: 1267528