[ROCm] define C10_WARP_SIZE to warpSize HIP constant (#64302)

[ROCm] define C10_WARP_SIZE to warpSize HIP constant (#64302)

Summary:
warpSize is defined as a constexpr in HIP headers.  It is incorrect to assume warpSize 64.  This change fixes the C10_WARP_SIZE definition in torch sources similar to [how it was done in caffe2](https://github.com/pytorch/pytorch/blob/master/caffe2/utils/GpuDefs.cuh#L10-L14).

cc jeffdaily sunway513 jithunnair-amd ROCmSupport

Pull Request resolved: https://github.com/pytorch/pytorch/pull/64302

Reviewed By: mrshenli

Differential Revision: D30785975

Pulled By: malfet

fbshipit-source-id: 68f8333182ad4d02bd0c8d02f1751a50bc5bafa7