[GPU] Make permuteWeights inline (#47634)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47634
Follow up on d16r's diff - D24710102. Make the function inline in order to get rid of the compiler checking `-Werror,-Wunused-function`.
ghstack-source-id: 116607200
Test Plan:
1. Sandcastle Tests
2. CircleCI jobs
Reviewed By: d16r
Differential Revision: D24824637
fbshipit-source-id: c17e219b384b91ac4620aa23112a6cda1200a605
