Fix namespace typo. (#16021)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16021

Adds nom:: so that TRIVIAL_CONVERTER works more generally.

Reviewed By: janewangfb

Differential Revision: D13664748

fbshipit-source-id: 100f47a8326e41bd0ac2ae281669f5a0363fe060
diff --git a/caffe2/opt/converter.h b/caffe2/opt/converter.h
index 99e0039..4474d7f 100644
--- a/caffe2/opt/converter.h
+++ b/caffe2/opt/converter.h
@@ -62,7 +62,7 @@
   class opName##Converter : public Converter {                                \
     std::unique_ptr<nom::repr::NeuralNetOperator> convertToNeuralNetOperator( \
         const OperatorDef& op) override {                                     \
-      return util::make_unique<repr::opName>();                               \
+      return nom::util::make_unique<nom::repr::opName>();                     \
     }                                                                         \
     virtual ~opName##Converter() {}                                           \
   };