fake_quant cachemask: remove Python bindings (#51878)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51878
`fake_quantize_per_tensor_affine_cachemask` and
`fake_quantize_per_channel_affine_cachemask` are implementation
details of `fake_quantize_per_tensor_affine` and
`fake_quantize_per_channel_affine`, removing the
Python bindings for them since there is no need to
expose them.
Test Plan:
```
python test/test_quantization.py TestFakeQuantize
```
Imported from OSS
Reviewed By: albanD, bugra
Differential Revision: D26314173
fbshipit-source-id: 733c93a3951453e739b6ed46b72fbad2244f6e97
