StimBuff: Use a single StagingBuffer for all StimFrames

We now allocate all the stimFrames for a StimBuffer using a
single StagingBuffer. This gives us all the benefits we're
looking for (pinning, alignment, etc).

stimBuffApis/livoxGen1/pcloudAmbienceStimulusBuffer.h

@@ -23,11 +23,10 @@ public:
 		const std::shared_ptr<device::DeviceAttachmentSpec>& deviceAttachmentSpec,
 		int histbuffMs,
 		const StagingBuffer::IOEngineConstraints& inputEngineConstraints,
-		const StagingBuffer::IOEngineConstraints& outputEngineConstraints,
-		size_t nSlotsPerStimFrame)
+		const StagingBuffer::IOEngineConstraints& outputEngineConstraints)
 	:	StimulusBuffer(
 			parent, deviceAttachmentSpec, histbuffMs,
-			inputEngineConstraints, outputEngineConstraints, nSlotsPerStimFrame)
+			inputEngineConstraints, outputEngineConstraints)
 	{}
 
 	~PcloudAmbienceStimulusBuffer() = default;