audio: add VOICE_VOLUME ctl

Add a new PCM control operation to update the stream volume on the
audio backend.  The argument given is a SWVoiceOut/SWVoiceIn.

v4:
- verified other backends didn't fail/assert on this new control
  they randomly return 0 or -1, but we ignore return value.

Signed-off-by: Marc-Andr? Lureau <marcandre.lureau@redhat.com>
Signed-off-by: malc <av1474@comtv.ru>
diff --git a/audio/audio.c b/audio/audio.c
index 398763f..d76c342 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -2053,17 +2053,29 @@
 void AUD_set_volume_out (SWVoiceOut *sw, int mute, uint8_t lvol, uint8_t rvol)
 {
     if (sw) {
+        HWVoiceOut *hw = sw->hw;
+
         sw->vol.mute = mute;
         sw->vol.l = nominal_volume.l * lvol / 255;
         sw->vol.r = nominal_volume.r * rvol / 255;
+
+        if (hw->pcm_ops->ctl_out) {
+            hw->pcm_ops->ctl_out (hw, VOICE_VOLUME, sw);
+        }
     }
 }
 
 void AUD_set_volume_in (SWVoiceIn *sw, int mute, uint8_t lvol, uint8_t rvol)
 {
     if (sw) {
+        HWVoiceIn *hw = sw->hw;
+
         sw->vol.mute = mute;
         sw->vol.l = nominal_volume.l * lvol / 255;
         sw->vol.r = nominal_volume.r * rvol / 255;
+
+        if (hw->pcm_ops->ctl_in) {
+            hw->pcm_ops->ctl_in (hw, VOICE_VOLUME, sw);
+        }
     }
 }