[lint] small pass to make lint clean (#68367)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68367
- bmm_test.py was using syntax not allowed in 3.6
- Some suppressions were not placed on the correct line.
With this file,
```
lintrunner --paths-cmd='git grep -Il .'
```
passes successfully.
Test Plan: Imported from OSS
Reviewed By: janeyx99, mrshenli
Differential Revision: D32436644
Pulled By: suo
fbshipit-source-id: ae9300c6593d8564fb326822de157d00f4aaa3c2
