[DDP] Remove SPMD from self.modules_buffers (#64474)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64474
No need for a nested list here.
ghstack-source-id: 137526312
Test Plan: CI
Reviewed By: zhaojuanmao
Differential Revision: D30745960
fbshipit-source-id: 66a8f9847e9fe1e02c51b79647e93bf7665cf4d9
