Enable CSR inputs for torch.sparse.mm (#73075)
Summary:
Previously `torch.sparse.mm` supported only COO and dense inputs.
Computing derivatives works wrt dense input for sparse_csr x dense -> dense
Modified implementation of `torch.sparse.mm` to be directly bound to ATen function.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73075
Reviewed By: mikaylagawarecki
Differential Revision: D34342954
Pulled By: cpuhrsch
fbshipit-source-id: a6ed914a0ce28b35276109479109095f7149d32b
(cherry picked from commit 948de1816c46cd087bacbee36dc583cf409813f9)
