Revert D27422219: [caffe2] Support Log1p operator
Test Plan: revert-hammer
Differential Revision:
D27422219 (https://github.com/pytorch/pytorch/commit/d92e2520dee8329d5839f5aaf49f51e50a5b8a97)
Original commit changeset: f9eba82bf09c
fbshipit-source-id: 7cd5b778ae5f296187f57b6efaa782de97a6f013
