[ROCm] remove thrust workaround in ScanKernels (#44553)
Summary:
Remove ROCm workaround added in https://github.com/pytorch/pytorch/issues/39180.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44553
Reviewed By: mruberry
Differential Revision: D23663988
Pulled By: ngimel
fbshipit-source-id: 71b2fd7db006d9d3459b908a996c4d96838ba742
