Remove default values from functional overloads for activation, batchnorm, distance, embedding
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/29456
Test Plan: Imported from OSS
Differential Revision: D18401483
Pulled By: yf225
fbshipit-source-id: 638ff72a60fb69e41bec6f468835654b208c2896
