Revert D30360382: [nnc] Support thread level parallelism in fused kernels
Test Plan: revert-hammer
Differential Revision:
D30360382 (https://github.com/pytorch/pytorch/commit/d6d86efb1c839ddafd1398d6dab9caa4f31a9f0b)
Original commit changeset: 29acf4e932c6
fbshipit-source-id: e0531113135d30eabb172dc1537d5dd6d65dc438
