Fix name of the platform (#1241)
Summary:
The name of the platform will be embeded in the scribe upload object, so we want to keep it consistent with the format used in scribe.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1241
Reviewed By: weatfb
Differential Revision: D40321929
Pulled By: xuzhao9
fbshipit-source-id: e7d61ab0a0945e2e43277fe798d5455249a6e110
