dbus: Fix logic when registering manager object
dbus: Fix logic when registering manager object

Introduced by commit 1d7f9a585135da5e5ddb8f52ca0d55d93b4b0405

CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source