LG1PCloudAmbStncl: Use RangeDescriptor obj instead of StagingBuffer

We directly use an instance of RangeDescriptor to avoid incurring
the memory cost of using a StagingBuffer here. It's unnecessary
since these stencils will always be 32bits large.

include/user/pcloudAmbienceStencil.h

@@ -18,16 +18,6 @@ class PcloudAmbienceStencil
 public:
 	typedef uint32_t PcloudAmbienceStimulusValue;
 
-	/**
-	 * RangeDescriptor describes a contiguous range of body spots for
-	 * point cloud ambience stencils.
-	 */
-	struct RangeDescriptor : public Stencil::RangeDescriptor
-	{
-		uint32_t bodySpot;
-		size_t nContiguousSpots;
-	};
-
 	PcloudAmbienceStencil() = default;
 	virtual ~PcloudAmbienceStencil() = default;
 };