[C++] remove unnecessary if block in PublicationManager::broadcastOccurred
[C++] remove unnecessary if block in PublicationManager::broadcastOccurred

return value of getTimeUntilNextPublication is always >= 0

Change-Id: I148dfae18e1573705de9afd8f81fc3f7c76f0d38

bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr