Use call to report state when ovs_agent starts up

Make sure to report ovs_agent state when starting up, otherwise
ovs_agent start_time would not be updated and thus l2pop does
not send fdb entries.

Change-Id: Idd770a85a9eabff112d9613e75d8bb524020234a
Closes-Bug: #1347452
Merge "Use call to report state when ovs_agent starts up"