Fix a typo when calculating tessCoordY in NGG compaction mode

The tessCoordY is mistakenly written with tessCoordX, leading to wrong
value of tessCoordY when NGG compaction mode is turned on. This issue is
found by TessMark.

Author: amdrexu

lgc/patch/NggPrimShader.cpp

@@ -3290,7 +3290,7 @@ Value *NggPrimShader::runPartEs(ArrayRef<Argument *> args, Value *position) {
           tessCoordX = createPhi({{newTessCoordX, uncompactVertexBlock}, {tessCoordX, exportVertexBlock}});
 
         if (newTessCoordY)
-          tessCoordX = createPhi({{newTessCoordY, uncompactVertexBlock}, {tessCoordY, exportVertexBlock}});
+          tessCoordY = createPhi({{newTessCoordY, uncompactVertexBlock}, {tessCoordY, exportVertexBlock}});
 
         assert(newRelPatchId);
         relPatchId = createPhi({{newRelPatchId, uncompactVertexBlock}, {relPatchId, exportVertexBlock}});