Fix comment

Author: clementval

flang/lib/Optimizer/CodeGen/TargetRewrite.cpp

@@ -528,7 +528,7 @@ class TargetRewrite : public fir::impl::TargetRewritePassBase<TargetRewrite> {
                                callOp.getDynamicSharedMemorySize(), newOpers,
                                asyncToken ? asyncToken.getType() : nullptr,
                                callOp.getAsyncDependencies(),
-                               /**/ std::nullopt);
+                               /*clusterSize=*/std::nullopt);
       if (callOp.getClusterSizeX())
         newCall.getClusterSizeXMutable().assign(callOp.getClusterSizeX());
       if (callOp.getClusterSizeY())