adjust sound volume in kde live cd

[hlyg <hlyg2023@outlook.com>]

i find trixie kde live cd of practical use even without installation to 
hard disk

i can play sound but can't adjust sound volume

in right bottom of desktop, red bar is over speaker icon, which means 
disabled

it finds no input/output device, it uses dummy device

it works well in early debian distro, lspci:

Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High 
Definition Audio Controller (rev 04)