Fix issue re: DDP and create_graph=True (#63831)

Fix issue re: DDP and create_graph=True (#63831)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63831

Closes https://github.com/pytorch/pytorch/issues/63812

`at::mul_out` is not supported when `grad` itself requires grad, which is useful for computing higher order derivatives.

In this case, fall back to a mul + copy instead of mul_out.
ghstack-source-id: 136614644

Test Plan: UT

Reviewed By: SciPioneer

Differential Revision: D30505573

fbshipit-source-id: 83532b6207b3d80116fcc4dff0e5520d73b3454f