Check statstical diff rather than exact match for test_dropout_cuda. (#40883)
Summary:
There's is a TODO tracked in https://github.com/pytorch/pytorch/issues/40882
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40883
Reviewed By: pbelevich
Differential Revision: D22346087
Pulled By: ailzhang
fbshipit-source-id: b4789ca3a10f6a72c6e77276bde45633eb6cf545
