Remove native_functions.yaml dependency from PowKernel (#64171)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/64171
Test Plan: Imported from OSS
Reviewed By: gchanan
Differential Revision: D30728583
Pulled By: dagitses
fbshipit-source-id: ea6891a3598eead93daea620b94e50d3a3b248cf
