message: Replace slow GPU API call in GetGpu3DLaunchConfig
  cudaGetDeviceProperties is a heavy-weight call. This commit replaces
  it with individual calls to cudaDeviceGetAttribute, which are much
  faster.
  This is important here because the enclosing function is called for
  each kernel launch (for those ops that use it).
diff: @@ -276,21 +276,25 @@ Gpu3DLaunchConfig GetGpu3DLaunchConfig(int xdim, int ydim, int zdim,
  }
  int dev;
  + int xthreadlimit = 0, ythreadlimit = 0, zthreadlimit = 0;
  + int xgridlimit = 0, ygridlimit = 0, zgridlimit = 0;
  #if GOOGLE_CUDA
  cudaGetDevice(&dev);
  - cudaDeviceProp deviceProp;
  - cudaGetDeviceProperties(&deviceProp, dev);
  + cudaDeviceGetAttribute(&xthreadlimit, cudaDevAttrMaxBlockDimX, dev);
  + cudaDeviceGetAttribute(&ythreadlimit, cudaDevAttrMaxBlockDimY, dev);
  + cudaDeviceGetAttribute(&zthreadlimit, cudaDevAttrMaxBlockDimZ, dev);
  + cudaDeviceGetAttribute(&xgridlimit, cudaDevAttrMaxGridDimX, dev);
  + cudaDeviceGetAttribute(&ygridlimit, cudaDevAttrMaxGridDimY, dev);
  + cudaDeviceGetAttribute(&zgridlimit, cudaDevAttrMaxGridDimZ, dev);
  #elif TENSORFLOW_USE_ROCM
  hipGetDevice(&dev);
  - hipDeviceProp_t deviceProp;
  - hipGetDeviceProperties(&deviceProp, dev);
  + hipDeviceGetAttribute(&xthreadlimit, hipDeviceAttributeMaxBlockDimX, dev);
  + hipDeviceGetAttribute(&ythreadlimit, hipDeviceAttributeMaxBlockDimY, dev);
  + hipDeviceGetAttribute(&zthreadlimit, hipDeviceAttributeMaxBlockDimZ, dev);
  + hipDeviceGetAttribute(&xgridlimit, hipDeviceAttributeMaxGridDimX, dev);
  + hipDeviceGetAttribute(&ygridlimit, hipDeviceAttributeMaxGridDimY, dev);
  + hipDeviceGetAttribute(&zgridlimit, hipDeviceAttributeMaxGridDimZ, dev);
  #endif
  - int xthreadlimit = deviceProp.maxThreadsDim[0];
  - int ythreadlimit = deviceProp.maxThreadsDim[1];
  - int zthreadlimit = deviceProp.maxThreadsDim[2];
  - int xgridlimit = deviceProp.maxGridSize[0];
  - int ygridlimit = deviceProp.maxGridSize[1];
  - int zgridlimit = deviceProp.maxGridSize[2];
  int block_count = 0;
  int thread_per_block = 0;
  