gen_amd_libdevice_extra.py --out cannot accept a file path

### Description

`python/triton_dist/tools/gen_amd_libdevice_extra.py --help` describes `--out` as a file path, but the option is configured with `action="store_true"`.

### Reproduction

At main commit `8260bc34398c2b8f36dc840fd22f741ca9294584`:

```console
$ python python/triton_dist/tools/gen_amd_libdevice_extra.py --out /tmp/libdevice-extra.ll
gen_amd_libdevice_extra.py: error: unrecognized arguments: /tmp/libdevice-extra.ll
```

Passing the bare flag also fails because `open(True)` treats the boolean as file descriptor 1:

```console
$ python python/triton_dist/tools/gen_amd_libdevice_extra.py --out
RuntimeWarning: bool is used as a file descriptor
io.UnsupportedOperation: not writable
```

Omitting `--out` still prints the generated LLVM IR to standard output.

### Expected behavior

`--out PATH` should write the generated LLVM IR to `PATH`, matching the command's help text, while omitting the option should continue writing to standard output.

Start with python/triton_dist/tools/gen_amd_libdevice_extra.py and compare the --help description with how the --out argument is parsed and opened. Run the reported command with a temporary PATH and without --out; done means the path receives the generated LLVM IR while the omitted option still writes it to standard output.

Written by the indexing model from the issue text.