OpInfo for `nn.functional.dropout2d`, revise sample inputs for `dropout` (#67891)
Summary:
Earlier, we were only testing for inputs with the shape of `(5,)` for `nn.functional.dropout`, but since it's used a lot - I feel it's a good idea to test for a few more shapes including scalars. This PR:
1. Revises sample inputs for `nn.functional.dropout`
2. Adds an OpInfo for `nn.functional.dropout2d`.
A note regarding the documentation:
Looks like `nn.functional.dropout2d` also supports inputs of shape `(H, W)` apart from `(N, C, H, W) / (C, H, W)` but the [documentation](https://pytorch.org/docs/stable/generated/torch.nn.Dropout2d.html#torch.nn.Dropout2d) doesn't mention that (`H, W` case). Should that be revised or am I missing anything here? (Filed an issue here: https://github.com/pytorch/pytorch/issues/67892)
```python
# A 2D tensor is a valid input for Dropout2d
In [11]: tensor = torch.randn((3, 4), device='cpu', dtype=torch.float32)
In [12]: dropout2d = torch.nn.Dropout2d(p=0.5)
In [13]: dropout2d(tensor)
Out[13]:
tensor([[-0.1026, -0.0000, -0.0000, -0.0000],
[-1.5647, 0.0000, -0.0000, -0.5820],
[-0.0000, -3.2080, 0.1164, -3.6780]])
```
Issue Tracker: https://github.com/pytorch/pytorch/issues/54261
cc: mruberry zou3519
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67891
Reviewed By: mrshenli
Differential Revision: D32628527
Pulled By: mruberry
fbshipit-source-id: 4c9b89550f1d49526e294378ce107eba9f29cabb
