pulseaudio: process audio data in smaller chunks

pulseaudio: process audio data in smaller chunks

The rate of pulseaudio absorbing the audio stream is used to control the
the rate of the guests audio stream.  When the emulated hardware uses
small chunks (like intel-hda does) we need small chunks on the audio
backend side too, otherwise that feedback loop doesn't work very well.

Cc: Max Ehrlich <[email protected]>
Cc: Martin Schrodt <[email protected]>
Buglink: https://bugs.launchpad.net/bugs/1795527
Signed-off-by: Gerd Hoffmann <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: 20181109142032[email protected]