fx quant: add types to quantization_patterns (#48851)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48851
Adding typing to improve readability.
Note: this uncovered a few missing return statements, we should
fix that before landing.
Test Plan:
```
mypy torch/quantization/
```
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D25338644
fbshipit-source-id: 0ac4405db05fdd2737bc3415217bc1937c2db684
