Fix nvfuser benchmarks (#915)
Summary:
Followup from https://github.com/pytorch/benchmark/issues/914, an import path needed to be updated.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/915
Reviewed By: xuzhao9
Differential Revision: D36426002
Pulled By: davidberard98
fbshipit-source-id: 14a9d0eec1c7f3849dfa861b03c10376c812fb65
