Use torch.set_default_dtype in test_data_parallel and rename dtype2prec (#32962)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32962
As per gchanan's comments on
https://github.com/pytorch/pytorch/pull/30445, I've used
`torch.set_default_dtype` in test_data_parallel instead of specifying
dtype=torch.double everywhere. Also, renamed dtype2prec to dtype2prec_DONTUSE
ghstack-source-id: 98388429
Test Plan: waitforbuildbot
Differential Revision: D19714374
fbshipit-source-id: eb55bbca33881625636ba9ea6dd4cb692f25668e
