OVSDriver: handle link status changes for new/delete also
OVSDriver: handle link status changes for new/delete also

It's possible for the link-add Netlink message to arrive after the openvswitch
vport-add Netlink message, and to carry a status change such as link-up. The
previous code would have dropped this message and never seen a link-up
notification for that port.

vezril/ivs,floodlight/ivs,floodlight/ivs,floodlight/ivs,vezril/ivs,vezril/ivs