alsa: Fixes Bug#13087 - module removal & path correction for asound.state file

alsa: Fixes Bug#13087 - module removal & path correction for asound.state file

- start_service added to install.sh and stop_service to uninstall.sh
   This ensures that the modules are loaded after install
- The /etc/asound.state file was touched by the install.sh cript but the alsactl store and
   restore commands have default location of /var/lib/alsa/ so the touch command created
   an asound.state file that was then not used subsequently. It also meant that the first
   start of alsa would fail as it would try and restore from /var/lib/alsa/asound.state
   but the file did not exist.
- This patch corrects the path for the touch command for asound.state
- The install.sh script also checks if /etc/asound.state, that was never used, exists and
   if it does removes it.
- Uninstalling alsa left the sound modules installed until a reboot was carried out.
   Uninstallation should unload the alsa kernel modules.
   This patch adds the modprobe -r commands to the uninstall.sh file to unload all the snd
   modules when alsa is uninstalled.
- make_backup and restore_backup commands added to ther install.sh and uninstall.sh scripts

Fixes: Bug#13087
Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>