Wextra fix for NamedTensor.cpp (#66897)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66897
Fixes:
```
stderr: caffe2/aten/src/ATen/native/NamedTensor.cpp:226:19: error: comparison of integers of different signs: 'const unsigned long' and 'int64_t' (aka 'long') [-Werror,-Wsign-compare]
if (order_idx >= ellipsis_idx) {
~~~~~~~~~ ^ ~~~~~~~~~~~~
stderr: caffe2/aten/src/ATen/native/NamedTensor.cpp:226:19: error: comparison of integers of different signs: 'const unsigned long' and 'int64_t' (aka 'long') [-Werror,-Wsign-compare]
if (order_idx >= ellipsis_idx) {
~~~~~~~~~ ^ ~~~~~~~~~~~~
```
Test Plan: Sandcastle
Reviewed By: malfet
Differential Revision: D31774623
fbshipit-source-id: b6e5b76695e512084ac5c9cb4215de7e9b763cf8
