Revert D24853669: [pytorch][PR] Migrate `eig` from the TH to Aten (CUDA)
Test Plan: revert-hammer
Differential Revision:
D24853669 (https://github.com/pytorch/pytorch/commit/866f8591be5f4121a217d31ed7734bf121592192)
Original commit changeset: a513242dc7f4
fbshipit-source-id: a0c8c424b61b1e627d9102de6b4c6d0717a6c06d
