datapath: Tunnel port without destination IP.

datapath: Tunnel port without destination IP.

Following patch allow port create without any parameters. This is
required for compatibility with future flow based tunneling
where each type would have single vport with all parameter
wild carded. So that all packet for all ports are received on
the port and same port is used for sending all traffic for
that tunnel type.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Kyle Mestery <kmestery@cisco.com>
Acked-by: Ben Pfaff <blp@nicira.com>