Use default scale/zero_point in fake_quantize module instead of None (#32318)
Summary:
Distributed data parallel can not broadcast None so when we prepare the model for QAT and trying to save the model it will error out.
fixes: https://github.com/pytorch/pytorch/issues/32082
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32318
Differential Revision: D19434801
Pulled By: jerryzh168
fbshipit-source-id: ee70abe4c3dcdd3506fb7dd0316aee2fb1705469
