sys/sunaudio/: Fix up the mixer tracks to use a volume range of 0-255, which is what...

sys/sunaudio/: Fix up the mixer tracks to use a volume range of 0-255, which is what the sun audio API uses. This sim...

Original commit message from CVS:
Patch by: Brian Cameron <brian.cameron at sun dot com>
* sys/sunaudio/gstsunaudiomixerctrl.c:
(gst_sunaudiomixer_ctrl_get_volume),
(gst_sunaudiomixer_ctrl_set_volume):
* sys/sunaudio/gstsunaudiomixertrack.c: (gst_sunaudiomixer_track_new):
Fix up the mixer tracks to use a volume range of 0-255, which is what
the sun audio API uses. This simplifies the code and avoids rounding
errors. Fixes #524593.