[ROCm] do not use __shfl sync functions

This avoids a static_assert compile-time failure for HIP.

Author: jeffdaily

csrc/cuda/utils.cuh

@@ -6,6 +6,7 @@
   AT_ASSERTM(x.device().is_cuda(), #x " must be CUDA tensor")
 #define CHECK_INPUT(x) AT_ASSERTM(x, "Input mismatch")
 
+#ifndef USE_ROCM
 __device__ __inline__ at::Half __shfl_up_sync(const unsigned mask,
                                               const at::Half var,
                                               const unsigned int delta) {
@@ -17,6 +18,7 @@ __device__ __inline__ at::Half __shfl_down_sync(const unsigned mask,
                                                 const unsigned int delta) {
   return __shfl_down_sync(mask, var.operator __half(), delta);
 }
+#endif
 
 __device__ __inline__ at::Half __shfl_up(const at::Half var,
                                          const unsigned int delta) {