Falcon: make activation, ffn_hidden_size configurable
Author: sshleifer
Pull request: yes

Defaults unchanged

Comments:
I fixed `ruff check examples tests src utils`
Dont know how to fix `python utils/check_docstrings.py`. On my mac it raises
```
[1]    44425 illegal hardware instruction  python utils/check_docstrings.py
```

The docstring traceback is

```
2024-04-09 19:02:18.387924: W tensorflow/compiler/tf2tensorrt/utils/py_utils.cc:38] TF-TRT Warning: Could not find TensorRT
/home/circleci/transformers/src/transformers/deepspeed.py:23: FutureWarning: transformers.deepspeed module is deprecated and will be removed in a future version. Please import deepspeed modules directly from transformers.integrations
  warnings.warn(
Traceback (most recent call last):
  File "utils/check_docstrings.py", line 1249, in <module>
    check_docstrings(overwrite=args.fix_and_overwrite)
  File "utils/check_docstrings.py", line 1241, in check_docstrings
    raise ValueError(error_message)
ValueError: There was at least one problem when checking docstrings of public objects.
The following objects docstrings do not match their signature. Run `make fix-copies` to fix this. In some cases, this error may be raised incorrectly by the docstring checker. If you think this is the case, you can manually check the docstrings and then add the object name to `OBJECTS_TO_IGNORE` in `utils/check_docstrings.py`.
- FalconConfig
- ```

> I fixed `ruff check examples tests src utils` Dont know how to fix `python utils/check_docstrings.py`. On my mac it raises
> 
> ```
> [1]    44425 illegal hardware instruction  python utils/check_docstrings.py
> ```

I really have no idea on this one :/ We had a similar issue opened here #17402. At the time, it was related to TF installations on the mac. 

I would try creating a new env and reinstalling with `pip install -e .[torch,testing]`

> The docstring traceback is
> 
> ```
> 2024-04-09 19:02:18.387924: W tensorflow/compiler/tf2tensorrt/utils/py_utils.cc:38] TF-TRT Warning: Could not find TensorRT
> /home/circleci/transformers/src/transformers/deepspeed.py:23: FutureWarning: transformers.deepspeed module is deprecated and will be removed in a future version. Please import deepspeed modules directly from transformers.integrations
>   warnings.warn(
> Traceback (most recent call last):
>   File "utils/check_docstrings.py", line 1249, in <module>
>     check_docstrings(overwrite=args.fix_and_overwrite)
>   File "utils/check_docstrings.py", line 1241, in check_docstrings
>     raise ValueError(error_message)
> ValueError: There was at least one problem when checking docstrings of public objects.
> The following objects docstrings do not match their signature. Run `make fix-copies` to fix this. In some cases, this error may be raised incorrectly by the docstring checker. If you think this is the case, you can manually check the docstrings and then add the object name to `OBJECTS_TO_IGNORE` in `utils/check_docstrings.py`.
> - FalconConfig
> - ```
> ```

Have you been able to run `make fix-copies`?

I think I got it, just ran everything in linux.
Now make fix copies only complains about other models
```
python utils/check_copies.py --fix_and_overwrite
Detected changes, rewriting src/transformers/models/bigbird_pegasus/modeling_bigbird_pegasus.py.
Detected changes, rewriting src/transformers/models/cohere/modeling_cohere.py.
Detected changes, rewriting src/transformers/models/gemma/modeling_gemma.py.
Detected changes, rewriting tests/models/roc_bert/test_tokenization_roc_bert.py.
python utils/check_table.py --fix_and_overwrite
python utils/check_dummies.py --fix_and_overwrite
python utils/check_doctest_list.py --fix_and_overwrite
python utils/check_task_guides.py --fix_and_overwrite
python utils/check_docstrings.py --fix_and_overwrite
```

Do I need another approval?
<img width="976" alt="image" src="https://github.com/huggingface/transformers/assets/6045025/02e03a28-ca46-4402-b54f-5fd98c2bf8fa">


@LysandreJik 

> Now make fix copies only complains about other models

Hmmm, that's weird, there shouldn't be any changes to those models as they don't copy from Falcon 🤔  What do you see in the diff from running `make fix-copies`? 

> Do I need another approval?

No, this is for running the doctest and is guarded for security reasons. I can run them, but we don't need to for this PR. It takes a long time, so it's better to just skip if not needed 

Rebase fixed it. Now it doesnt complain !
Thanks for the help :) 
(this is from my fork)
![image](https://github.com/huggingface/transformers/assets/6045025/d8ccc75b-1e49-4d58-9579-4a437e4549e3)


Are we good to merge?