Audio over 3.5mm jack on OSMC/Kodi Matrix

Unfortunately the 'Audio over 3.5mm jack' option disappeared in the latest OSMC/Kodi.

Reenable it by editing the file /boot/config-user.txtand add

dtoverlay=pisound
dtparam=audio=on

...

sudo apt-get update
sudo apt-get install alsa-utils
alsamixer