[FX] Fix submodule naming for subgraph split (#47869)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/47869
Test Plan: Imported from OSS
Reviewed By: scottxu0730
Differential Revision: D24925283
Pulled By: jamesr66a
fbshipit-source-id: a33bff20667405a3bbfc81e1e640c2649c0db03b
