Revert D25734450: [pytorch][PR] Improve `torch.flatten` docs and add tests to test_view_ops
Test Plan: revert-hammer
Differential Revision:
D25734450 (https://github.com/pytorch/pytorch/commit/730965c246192c94c804e5ac4a95f175dca2fb18)
Original commit changeset: 993667dd07ac
fbshipit-source-id: 603af25311fc8b29bb033167f3b2704da79c3147
