Inductor cpp wrapper: fix codegen of positional args with default value (#108552)
Fixes https://github.com/pytorch/pytorch/issues/108323.
Cpp wrapper has functionality regression on `llama` and `tnt_s_patch16_224` due to recent support of scaled dot product flash attention in inductor.
The schema of this OP is as follows:
```
- func: _scaled_dot_product_flash_attention(Tensor query, Tensor key, Tensor value, float dropout_p=0.0, bool is_causal=False, bool return_debug_mask=False, *, float? scale=None) -> (Tensor output, Tensor logsumexp, Tensor cum_seq_q, Tensor cum_seq_k, int max_q, int max_k, Tensor philox_seed, Tensor philox_offset, Tensor debug_attn_mask)
```
For `llama` and `tnt_s_patch16_224`, the OP is called in the below way, where the three positional args with default values are not passed (`float dropout_p=0.0, bool is_causal=False, bool return_debug_mask=False`).
```python
y = torch.ops.aten._scaled_dot_product_flash_attention.default(x0, x1, x2, scale = 0.125)
```
This PR fixes the cpp wrapper support for this case.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108552
Approved by: https://github.com/jgong5, https://github.com/desertfire, https://github.com/jansel
