Remove finput and fgrad_input from slow3d signatures (#68897)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/68897
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D32655875
Pulled By: jbschlosser
fbshipit-source-id: 8d04968b2df47e11da1eceb1612d55d00768eeb4
