Add back cudaHostRegister to cudart API. (#34665)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34665
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Differential Revision: D20493861
Pulled By: ezyang
fbshipit-source-id: 4215e3037a16be460f20cfc2859be5ee074128d3
