[nomnigraph] Copy device option when customize the op conversion (#34976)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34976
Previously, we are dropping the original device option info when we override the operator conversion function.
Test Plan:
```
buck test caffe2/caffe2/opt:converter_nomigraph_test
```
Reviewed By: ipiszy
Differential Revision: D20507277
fbshipit-source-id: 66b5eab07d18651eff27dab2a809cd04872ac224
