datapath: Added debug for port and flow adds/deletes

* Added debug level logs for normal conditions
* Added error level logs for error conditions

Change-Id: I09db4b9042ba989bd8e877322706d1be268a9438
Signed-off-by: Kevin Traynor <kevin.traynor@intel.com>
Reviewed-By: Stephen Finucane <stephen.finucane@intel.com>