Wextra fix for CUDAApplyUtils.cuh (#66323)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66323
Fixes
```
/data/sandcastle/boxes/eden-trunk-hg-fbcode-fbsource/fbcode/caffe2/aten/src/ATen/cuda/CUDAApplyUtils.cuh:310:48: error: comparison of integers of different signs: 'unsigned long' and 'int' [-Werror,-Wsign-compare]
const IndexType bOffset = sizeof...(Offsets) < n ?
~~~~~~~~~~~~~~~~~~ ^ ~
/data/sandcastle/boxes/eden-trunk-hg-fbcode-fbsource/fbcode/caffe2/aten/src/ATen/cuda/CUDAApplyUtils.cuh:306:48: error: comparison of integers of different signs: 'unsigned long' and 'int' [-Werror,-Wsign-compare]
const IndexType aOffset = sizeof...(Offsets) < n ?
~~~~~~~~~~~~~~~~~~ ^ ~
```
Test Plan: Sandcastle
Reviewed By: ngimel
Differential Revision: D31505428
fbshipit-source-id: 326fa8f41f2b200981eddc5cab035b18536cd24e
