Add the MPS device for the runs. (#917)
Summary:
This adds MPS device to be passed for running the torchbench.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/917
Reviewed By: soulitzer
Differential Revision: D36482953
Pulled By: xuzhao9
fbshipit-source-id: d32595483dae7a3347ce4fa17dab73f4e724ab90
