fix cuda seed bug of class_center_sample traning on multi gpu

Author: GuoxiaWang

paddle/fluid/operators/class_center_sample_op.cu

@@ -397,7 +397,9 @@ class ClassCenterSampleCUDAKernel : public framework::OpKernel<T> {
  (NumBlocks(num_classes) * kNumCUDAThreads * vec_size) +
  1) *
  vec_size;
- auto gen_cuda = framework::GetDefaultCUDAGenerator(rank);
+ int device_id =
+ BOOST_GET_CONST(platform::CUDAPlace, ctx.GetPlace()).GetDeviceId();
+ auto gen_cuda = framework::GetDefaultCUDAGenerator(device_id);
  if (gen_cuda->GetIsInitPy() && (!fix_seed)) {
  auto seed_offset = gen_cuda->IncrementOffset(offset);
  seed_data = seed_offset.first;