fix topk with k=0 on cuda (#58086)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/58086
Test Plan: Imported from OSS
Reviewed By: ngimel
Differential Revision: D28364964
Pulled By: bdhirsh
fbshipit-source-id: 4d02bf5b27ca5e8b6f7b6cc6aa99d9e31233578b
