[MLIR] Apply clang-tidy fixes for llvm-qualified-auto in LowerGpuOpsToNVVMOps.cpp (NFC)

Author: joker-eph

mlir/lib/Conversion/GPUToNVVM/LowerGpuOpsToNVVMOps.cpp

@@ -398,7 +398,7 @@ struct LowerGpuOpsToNVVMOpsPass final
       if (!allowedDialectsSet.empty() && !allowed)
         continue;
 
-      auto iface = dyn_cast<ConvertToLLVMPatternInterface>(dialect);
+      auto *iface = dyn_cast<ConvertToLLVMPatternInterface>(dialect);
       if (!iface) {
         // Error out if dialect was explicily specified but doesn't implement
         // conversion interface.