Corrected navigation sort in depth higher than 1

__Tasks:__

- [ ] test coverage
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation
- [ ] ... <add your own tasks>

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | fixes https://github.com/sulu-cmf/sulu-standard/issues/307
| BC Breaks     | none
| Doc           | none