add BFloat16 support for bernoulli and Dropout on CPU (#56372)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56372
Test Plan: Imported from OSS
Reviewed By: heitorschueroff
Differential Revision: D28836792
Pulled By: VitalyFedyunin
fbshipit-source-id: ede951d172a59276e11383fd767778ab959b5a6b
