Make native MHA private for release 1.11 (#72200)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72200
This op should still remain private in release 1.11, add underscore before op name to make it happens
Test Plan: buck run mode/opt -c fbcode.enable_gpu_sections=true pytext/fb/tools:benchmark_transformers -- mha --batch-size=10 --max-sequence-length=16
Reviewed By: bdhirsh
Differential Revision: D33952191
fbshipit-source-id: 3f8525ac9c23bb286f51476342113ebc31b8ed59
(cherry picked from commit 6e41bfa4fc242987165fafda1a01735838e3f73d)
