[Misc] Clean up the BitsAndBytes arguments (#15140)

Signed-off-by: Jee Jee Li <pandaleefree@gmail.com>

docs/source/features/quantization/bnb.md

@@ -25,7 +25,7 @@ import torch
 # unsloth/tinyllama-bnb-4bit is a pre-quantized checkpoint.
 model_id = "unsloth/tinyllama-bnb-4bit"
 llm = LLM(model=model_id, dtype=torch.bfloat16, trust_remote_code=True, \
-quantization="bitsandbytes", load_format="bitsandbytes")
+quantization="bitsandbytes")
 ```
 
 ## Inflight quantization: load as 4bit quantization
@@ -35,7 +35,7 @@ from vllm import LLM
 import torch
 model_id = "huggyllama/llama-7b"
 llm = LLM(model=model_id, dtype=torch.bfloat16, trust_remote_code=True, \
-quantization="bitsandbytes", load_format="bitsandbytes")
+quantization="bitsandbytes")
 ```
 
 ## OpenAI Compatible Server
@@ -43,5 +43,5 @@ quantization="bitsandbytes", load_format="bitsandbytes")
 Append the following to your 4bit model arguments:
 
 ```console
---quantization bitsandbytes --load-format bitsandbytes
+--quantization bitsandbytes
 ```