[docs] add docstring in torch.cuda.get_device_properties (#49792)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/49737
Added docstring in `torch.cuda.get_device_properties`
Added the `Returns` in `torch.cuda.get_device_name`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49792
Reviewed By: mruberry
Differential Revision: D25784046
Pulled By: ngimel
fbshipit-source-id: f88da02147f92c889398957fcaf22961d3bb1062
