Support nn.Module in cast_tensors
Summary:
It's useful to allow an argument to be an nn.Module, but to do so we
need the ability to cast it. I've just implemented it as a no-op, assuming
that the benchmark will do the right thing with any nn.Modules it creates.
Reviewed By: xuzhao9
Differential Revision: D62303092
fbshipit-source-id: 2e05c5af604f95f7b5aa1525391d60fb67dfe267
