OClCollMeshEngn: hide StagingBuffer's firstSlotOffset

stimBuffApis/livoxGen1/collateDgrams.cl

@@ -25,7 +25,6 @@ __kernel void collate(
 	__global uchar* assembly,
 	__global float* collation,
 	uint slotStride,
-	uint firstSlotOffset,
 	uint nPointsPerSlot,
 	uint nDgramsPerFrame)
 {
@@ -36,8 +35,7 @@ __kernel void collate(
 	if (slotIndex >= nDgramsPerFrame) { return; }
 
 	// Calculate slot address
-	__global uchar* slotStart = assembly + firstSlotOffset
-		+ (slotIndex * slotStride);
+	__global uchar* slotStart = assembly + (slotIndex * slotStride);
 
 	// Read data_type from offset 9 (1 byte)
 	uchar dataType = slotStart[9];