[caffe2] Use extended versions of cuDNN calls for SpatialBN
Summary: Using `cudnnBatchNormalizationForwardTrainingEx` and `cudnnBatchNormalizationBackwardEx` if cuDNN version is greater than 8.0.0.
Reviewed By: xw285cornell
Differential Revision: D26794173
fbshipit-source-id: dc4994375350f303a3fa0aee03255e8f8be1c605
