disabling persistent mode for cuDNN BN on NCHW (#30031)
Summary:
This is to help the bisecting for unstable convergence that https://github.com/pytorch/pytorch/issues/29997 targets, comparing to the other PR, this one is a smaller hammer (few lines of code change) and would facilitate our future repro/fix.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30031
Differential Revision: D18577624
Pulled By: VitalyFedyunin
fbshipit-source-id: 92a76cf5db24b25105395f80086d90d8e51dcc4b
