Make LinearPackedParams works with both torchscript and torch.package (#71656)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71656
Customized `__getstate__`/`__setstate__` didn't call super (torch.nn.Module), and won't restore attributes (e.g. `_modules`) after being serialized and deserialized via torch.package
After a few iteration, as it turns out, pack/unpack linear param has been supported in torchbind class already, no need to hack torch module anymore.
Test Plan: `buck test caffe2/test/:quantization -- test_linear_api`
Reviewed By: jerryzh168
Differential Revision: D33711086
fbshipit-source-id: 3a36d10c64b7da414d3657d2ef766bb9a9290ea9
(cherry picked from commit 6337b6c20747d661a3920bf553dcc911dfa77671)
