Fix some printf warnings in executor_runner.cpp (#1529)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/1529

Some compilers don't like passing enums as printf arguments without casting them first.

Reviewed By: larryliu0820

Differential Revision: D52528480

fbshipit-source-id: 8d572995ac4bbc52077d1e955b5b361168a8ec53