Unify gpu_support variable in python tests (#16748)
Summary:
Assign `has_gpu_support = has_cuda_support or has_hip_support` and make according changes in python tests.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16748
Differential Revision: D13983132
Pulled By: bddppq
fbshipit-source-id: ca496fd8c6ae3549b736bebd3ace7fa20a6dad7f
