[codemod][lowrisk] Fix deprecated use of 0/NULL (#120740)
Summary:
`nullptr` is typesafe. `0` and `NULL` are not. In the future, only `nullptr` will be allowed.
This diff helps us embrace the future _now_ in service of enabling `-Wzero-as-null-pointer-constant`.
Test Plan: Sandcastle
Reviewed By: meyering
Differential Revision: D54163060
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120740
Approved by: https://github.com/Skylion007
