[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
