Fix bug in baddbmm corner case (#33467) (#33538)
Summary:
Ensure `torch.baddbmm(c, a, b)` returns `beta*c` when `a @ b` has empty inner dimension.
Fixes https://github.com/pytorch/pytorch/issues/33467.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33538
Differential Revision: D20352352
Pulled By: albanD
fbshipit-source-id: a7021c1979f82402ecea4784d6cc39783392ea16
