Function malloc

paddle/fluid/framework/data_feed.h:451–455

  T* data() { return cu_buffer; }
  uint64_t size() { return buf_size; }
  void malloc(uint64_t size) {
    buf_size = size;
    CUDA_CHECK(
        cudaMalloc(reinterpret_cast<void**>(&cu_buffer), size * sizeof(T)));
  }
  void free() {
    if (cu_buffer != NULL) {
      CUDA_CHECK(cudaFree(cu_buffer));