Fix type promotion for trace on CPU. (#47305)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47305
Fixes https://github.com/pytorch/pytorch/issues/47127.
Ideally this would just use diag and sum (as the CUDA implementation does), but that seems to have performance problems, which I'll link in the github PR.
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D24729627
Pulled By: gchanan
fbshipit-source-id: 151b786b53e7b958f0929c803dbf8e95981c6884
