datapath-windows: Fix HvUpdateNic() to handle name changes

datapath-windows: Fix HvUpdateNic() to handle name changes

If the name of an internal or external NIC changes, we need to
disconnect the NIC from OVS since the name is the key. In this
change, we generate a link down event. It is as though we got a
call to HvDisconnectNic() for the old name and got a HvConnectNic()
for the new name.

Also, HvCreateNic() has been cleaned up to remove the code to look
for existing vport. We won't have a vport now since we'd have deleted
the vport in HvDeleteNic().

Signed-off-by: Nithin Raju <nithin@vmware.com>
Acked-by: Sairam Venugopal <vsairam@vmware.com>
Acked-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Signed-off-by: Gurucharan Shetty <guru@ovn.org>