Revert D17939700: Revert D17889288: [pytorch][PR] Migrate soft_margin_loss from the TH to Aten (CUDA+CPU)
Test Plan: revert-hammer
Differential Revision:
D17939700
Original commit changeset: 4fc6156ba388
fbshipit-source-id: dded0a2140d2c14cd2f2a574987ecc164b0e5bfe
