quant: make each line of fx/quantize.py <=80 chars (#48357)

Summary:
Pull Request resolved: #48357

Cleans up the long lines in `torch/quantization/fx/quantize.py`
to fit the 80 character limit, so it's easier to read and looks
better on FB's tools.

In the future we can consider adding a linter for this.

Test Plan:
CI

Imported from OSS

Reviewed By: jerryzh168

Differential Revision: D25140833

fbshipit-source-id: 78605d58eda0184eb82f510baec26685a34870e2