[quant][embedding qat] Fix bug enforcing quant_min <= zero_point <= quant_max for float zeropoint (#68852)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68852
When using a float zero_point in FakeQuant, such as for embeddings, it does not need to be between
quant_min and quant_max, as is enforced for integer zero_points.
This is because float zero_points are formulated as per:
```
xq = Round(Xf * inv_scale + zero_point),
Xq = Round((Xf - min) * inv_scale)
```
Test Plan:
pytest test/test_quantization.py -v -k "test_fake_quant_per_channel_qparam_range"
Imported from OSS
Reviewed By: supriyar
Differential Revision: D32645014
fbshipit-source-id: 96dc3ca6eef9cee60be6919fceef95c9f2759891
