[NNC] Update Buf on mutation instead of creating new ones (#57513)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/57513
Test Plan: Imported from OSS
Reviewed By: VitalyFedyunin
Differential Revision: D28226917
Pulled By: navahgar
fbshipit-source-id: 4e74c56a85b7aadc285b872b8ef8f8e26f31c8ce
