[Docs] https://github.com/open-mmlab/mmdeploy/blob/main/docs/zh_cn/02-how-to-run/prebuilt_package_windows.md

[tankchenggeng]

📚 The doc issue

示例说明中：TensorRT Example的示例代码如下：

from mmdeploy.apis import torch2onnx
from mmdeploy.apis.tensorrt import onnx2tensorrt
from mmdeploy.backend.sdk.export_info import export2SDK
import os

img = 'mmpretrain/demo/demo.JPEG'
work_dir = 'work_dir/trt/resnet'
save_file = 'end2end.onnx'
deploy_cfg = 'mmdeploy/configs/mmpretrain/classification_tensorrt_static-224x224.py'
model_cfg = 'mmpretrain/configs/resnet/resnet18_8xb32_in1k.py'
model_checkpoint = 'resnet18_8xb32_in1k_20210831-fbbb1da6.pth'
device = 'cpu'

1. convert model to IR(onnx)

torch2onnx(img, work_dir, save_file, deploy_cfg, model_cfg,
model_checkpoint, device)

2. convert IR to tensorrt

onnx_model = os.path.join(work_dir, save_file)
save_file = 'end2end.engine'
model_id = 0
device = 'cuda'
onnx2tensorrt(work_dir, save_file, model_id, deploy_cfg, onnx_model, device)

3. extract pipeline info for sdk use (dump-info)

export2SDK(deploy_cfg, model_cfg, work_dir, pth=model_checkpoint, device=device)

其中pytorch转onnx的过程，device设置的是cpu，但tesorrt的配置文件中，backend没有cpu的选项。导致报错如下：

raise ValueError(f'{device} is invalid for the backend {backend}')
ValueError: cpu is invalid for the backend tensorrt

Suggest a potential alternative/fix

是不是应该将这里改成cuda？