Fix: Notify only the right hosts

After e8ad36c8, notification are always runned on all hosts of play:
```
PLAY [all] ********************************************************************
TASK: [change deb7] ***********************************************************
changed: [deb7.inter.nos]
ok: [deb6.inter.nos]
NOTIFIED: [deb7] **************************************************************
changed: [deb6.inter.nos]
changed: [deb7.inter.nos]
```
This pull should fix