sink: Enable deferred volume for hw volume control.
sink: Enable deferred volume for hw volume control.

Make sure volume changes are applied in between writing to hardware
to avoid volume glitches. As the writing is blocking we cannot synchronize
the changes from main thread easily so better to apply the changes
when nothing is written.

[sink] Enable deferred volume for hw volume control. JB#53590

jusa/pulseaudio-modules-droid,jusa/pulseaudio-modules-droid,mer-hybris/pulseaudio-modules-droid,mer-hybris/pulseaudio-modules-droid