Bf16 matmul (#64619)
Summary:
Re-create PR to fix https://github.com/pytorch/pytorch/pull/61891.
Drop the support for addbmm.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64619
Reviewed By: jbschlosser
Differential Revision: D30902995
Pulled By: VitalyFedyunin
fbshipit-source-id: dc318d73adff8f6974c9752d0d097e69276f8206
