Fix mp serialization for integer nn.Parameter on CUDA (#56529)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/56342
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56529
Reviewed By: albanD
Differential Revision: D27896094
Pulled By: ngimel
fbshipit-source-id: fe817781eb7139ea57c78acfd56e7c11b61eb4ed
