[MLIR] Apply clang-tidy fixes for misc-use-internal-linkage in MlirReduceMain.cpp (NFC)

Author: joker-eph

mlir/lib/Tools/mlir-reduce/MlirReduceMain.cpp

@@ -26,9 +26,9 @@
 using namespace mlir;
 
 // Parse and verify the input MLIR file. Returns null on error.
-OwningOpRef<Operation *> loadModule(MLIRContext &context,
-                                    StringRef inputFilename,
-                                    bool insertImplictModule) {
+static OwningOpRef<Operation *> loadModule(MLIRContext &context,
+                                           StringRef inputFilename,
+                                           bool insertImplictModule) {
   // Set up the input file.
   std::string errorMessage;
   auto file = openInputFile(inputFilename, &errorMessage);