[ONNX] Modify softplus symbolic to support beta!=1 (#65001) (#66146)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66146
* Modify softplus symbolic to support beta!=1
* Remove parse args
Test Plan: Imported from OSS
Reviewed By: jansel
Differential Revision: D31424096
fbshipit-source-id: 971af54a28141737ccb17510ada03b0651be2a63
