USB audio/SiS7018: Set controls_count on list mix ioctl

Looks like it works with default controls count 128 on default Haiku
builds but force media-addons-server to crash in case KDEBUG_LEVEL is set
to 0. Thanks to Vitaly Diger for pointing out and testing this issue.

src/add-ons/kernel/drivers/audio/ac97/sis7018/Mixer.cpp

@@ -612,6 +612,8 @@ Mixer::ListMixControls(multi_mix_control_info* Info)
 		_CreateMIXControlGroup(Info, index, recordGroup, RecordControls[i]);
 	}
 
+	Info->control_count = index;
+
 	return B_OK;
 }
 

src/add-ons/kernel/drivers/audio/usb/AudioControlInterface.cpp

@@ -1855,6 +1855,8 @@ AudioControlInterface::ListMixControls(multi_mix_control_info* Info)
 			I != MixerControlsMap.End(); I++)
 		_ListMixControlsForMixerUnit(index, Info, I->Value());
 
+	Info->control_count = index;
+
 	return B_OK;
 }