[PyTorch] Add fused addmm path in linear for contiguous 3D input (#72728)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72728
If the input is 3D and contiguous, we can get a fused addmm by reshaping.
ghstack-source-id: 152278479
Test Plan: existing tests?
Reviewed By: zrphercule
Differential Revision: D34176407
fbshipit-source-id: 899f216cadcd782c3b1b046025228df04228c740
(cherry picked from commit e601c5a512baac3791aa6d514d784234275a8f03)
