Add dropout parameter to lora configuration (#599)

* Add dropout parameter to lora configuration

A dropout parameter has been added to the lora configuration settings in lora_config.yaml. The LoRALinear class in utils.py has been updated to take this new parameter. Additionally, a AttributeError: 'types.SimpleNamespace' object has no attribute 'prompt' related to `args.prompt` has been removed from lora.py.

* Update lora_config.yaml

Set dropout to 0.0 in the sample config file

* format

---------

Co-authored-by: Awni Hannun <awni@apple.com>

llms/mlx_lm/tuner/utils.py

@@ -32,7 +32,11 @@ def linear_to_lora_layers(
         )
 
     to_lora = lambda lin: LoRALinear.from_linear(
-        lin, r=config["rank"], alpha=config["alpha"], scale=config["scale"]
+        lin,
+        r=config["rank"],
+        alpha=config["alpha"],
+        scale=config["scale"],
+        dropout=config["dropout"],
     )
 
     keys = config.get("keys", None)