Computation of logical ports names fail when adding more than once ODL controller to VTN Coordinator

When more than one ODL Controller is configured to VTN Coordinator, the computation of logical port fails for the second controller. This will result in the user always viewing only the logical ports of the first controller.
Logical ports are used in creating portmaps and vlanmaps.

Workaround: The user can list the switches and ports, and can construct the logical port string by himself/herself and create portmap or vlanmap for the port.

The user will be able to list all switches belonging to all controllers and for every switch can list all ports, then compute the logical port in the below format.The logical port is of the format PP-OF:<switch_id>-<PORT_ID>. This can be used in creation of portmap/vlanmap API.