Fix auto_functionalize (#121990)
Differential Revision: D54964130
When we re-export, auto_functionalize HOP will be in the graph. Therefore, we need to implement proper functionalization rule for it. Since the content inside auto_functionalize is guaranteed be functional, it is ok to just fall through it.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/121990
Approved by: https://github.com/ydwu4, https://github.com/zou3519
