message: fix kernel error
diff: @@ -286,7 +286,7 @@ __global__ __launch_bounds__(default_dot_size) void multidot_kernel(
  const auto tidx = threadIdx.x;
  const auto tidy = threadIdx.y;
  const auto col_idx = blockIdx.x * default_dot_dim + tidx;
  - const auto num = ceildiv(num_rows, default_dot_dim);
  + const auto num = ceildiv(num_rows, gridDim.y);
  const auto start_row = blockIdx.y * num;
  const auto end_row =
  ((blockIdx.y + 1) * num > num_rows) ? num_rows : (blockIdx.y + 1) * num;
  