Remove unnecessary Ubuntu version checks (#61738)
Summary:
PR https://github.com/pytorch/pytorch/issues/5401 missed another Ubuntu version check in `cmake/MiscCheck.cmake`.
The check for available functions added by https://github.com/pytorch/pytorch/issues/5401 are already present below the code snippet that this PR deletes.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61738
Reviewed By: mrshenli
Differential Revision: D29757525
Pulled By: ezyang
fbshipit-source-id: 7f5f9312284973481a8b8a2b9c51cc09774722e9
