cudnn error: `cannot find device code`

I have installed cudnn 7 and compile tvm with USE_CUDNN=1. When I run test_cudnn.py, it generates error:

```
/home/hyw/mxnet-tvm/tvm/python/tvm/build_module.py:331: UserWarning: Specified target cuda, but cannot find device code, did you do bind?
  "Specified target %s, but cannot find device code, did you do bind?" % target)
```

OS: ubuntu 16.04
CUDA: 8.0

What could it be the reason?