Remove checks for CUDA 8 in LU-based tests (#20482)
Summary:
CUDA 8 is no longer supported and removed from CI, so these checks are irrelevant
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20482
Differential Revision: D15393438
Pulled By: ezyang
fbshipit-source-id: ac0979bf660b3314eec502c745e34ce4940bda0e
