fsodeviced: add mainvolume index to BunchOfMixerControls
fsodeviced: add mainvolume index to BunchOfMixerControls

slyon/debian-libfsoframework,slyon/debian-fso-usaged,slyon/debian-libfsoframework,slyon/debian-fso-deviced,slyon/debian-fso-usaged,slyon/debian-fso-deviced