fix batch size problem (#1045)
Summary:
When bs not specified, this repeat will leads to infinite loop in https://github.com/pytorch/benchmark/blob/main/.github/scripts/run-config.py#L91
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1045
Reviewed By: FindHao
Differential Revision: D38038216
Pulled By: xuzhao9
fbshipit-source-id: aa247fe04c8768117cc0da25269e342cb7cad756
