Audiodev configuration allows to set the length of the buffered data.
The setting was ignored and a constant value used instead.
This patch makes the code apply the setting properly, and uses the
previous default if nothing is supplied.

Signed-off-by: Martin Schrodt <martin@schrodt.org>
Message-id: 20190315084653.120020-2-martin@schrodt.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>