assure armbian-hardware-monitor starts after armbian-firmboot and excutes cleanup steps on system shutdown.

Since refactoring the services the `stop` case in [armbian-hardware-monitor](https://github.com/armbian/build/blob/master/packages/bsp/common/usr/lib/armbian/armbian-hardware-monitor#L163) has become useless since never executed.

I tried to nail this down some time ago but to no avail. `systemd` NOOB still.

Related: To get nicer log output it would be great if `armbian-hardware-monitor` could wait for `firstrun` and `resize2fs` services to finish before starting to log. Also no idea how to achieve this.