reduce memory usage for centered rmsprop (#24170)
Summary:
Reduce gpu memory usage by using in-place operation
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24170
Differential Revision: D16784495
Pulled By: vincentqb
fbshipit-source-id: 03820cdc9a3952b95b9af0f87d3a9bb0f21e9b4d
