Corrected the syntax of port_update call to NVSD agent

The parameters passed to the agent rpc port_update call in
NVSD plugin were wrong. It is corrected now.

Change-Id: I9ec8f74695b6ca813ffad9e33502d9a2e0bd1f92
Closes-Bug: 1318909
Merge "Corrected the syntax of port_update call to NVSD agent"