Fix -Wdeprecated-defintions + -Werror data_ptr complaints in kernels (#3639)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/3639

I couldn't build //xplat/executorch/examples/models/llama2:main because these flags are on by default in that environment.
ghstack-source-id: 226668848

Reviewed By: cccclai

Differential Revision: D57449759

fbshipit-source-id: 468568debc1c666b6c262f6c5918245d6eebaa44