Do not show cuda stats in autograd profiler when `use_cuda=False` (#29666)
Summary:
Example
```python
import torch
x = torch.randn(1)
with torch.autograd.profiler.profile(use_cuda=False) as prof:
x + x
print(prof.key_averages().table(sort_by='cpu_time_total'))
```
Before:
```
------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- ---------------
Name Self CPU total % Self CPU total CPU total % CPU total CPU time avg CUDA total % CUDA total CUDA time avg Number of Calls
------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- ---------------
add 100.00% 25.781ms 100.00% 25.781ms 25.781ms NaN 0.000us 0.000us 1
------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- ---------------
Self CPU time total: 25.781ms
CUDA time total: 0.000us
```
After:
```
------- --------------- --------------- --------------- --------------- --------------- ---------------
Name Self CPU total % Self CPU total CPU total % CPU total CPU time avg Number of Calls
------- --------------- --------------- --------------- --------------- --------------- ---------------
add 100.00% 25.037ms 100.00% 25.037ms 25.037ms 1
------- --------------- --------------- --------------- --------------- --------------- ---------------
Self CPU time total: 25.037ms
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29666
Differential Revision: D18458828
Pulled By: bddppq
fbshipit-source-id: d96ef4cec8b1e85b77c211292a3099048882734d
