QDeclarativeGeoWaypoint: Declare QQmlParserStatus interface

Fix warning:
declarativemaps\qdeclarativegeoroutemodel_p.h(270): Warning: Class QDeclarativeGeoWaypoint implements the interface QQmlParserStatus but does not list it in Q_INTERFACES. qobject_cast to QQmlParserStatus will not work!

Change-Id: I3e9d8e6a68a5bb644a9d6ded8982daffaf985c53
Reviewed-by: Paolo Angelelli <paolo.angelelli@qt.io>