Remove `balance` and `devices` parameter from Pipe. (#48432)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48432
As per our design in https://github.com/pytorch/pytorch/issues/44827,
changign the API such that the user places modules on appropriate devices
instead of having a `balance` and `devices` parameter that decides this.
This design allows us to use RemoteModule in the future.
ghstack-source-id: 117491992
ghstack-source-id: 117491992
Test Plan: waitforbuildbot
Reviewed By: mrshenli
Differential Revision: D25172970
fbshipit-source-id: 61ea37720b92021596f69788e45265ac9cd41746
