[Misc] Merge bitsandbytes_stacked_params_mapping and packed_modules_mapping (#11924)

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

vllm/model_executor/models/gemma.py

@@ -349,15 +349,6 @@ class GemmaForCausalLM(nn.Module, SupportsLoRA, SupportsPP):
         "gate_up_proj",
         "down_proj",
     ]
-    # BitandBytes specific attributes
-    bitsandbytes_stacked_params_mapping = {
-        # shard_name, weight_name, index
-        "q_proj": ("qkv_proj", 0),
-        "k_proj": ("qkv_proj", 1),
-        "v_proj": ("qkv_proj", 2),
-        "gate_proj": ("gate_up_proj", 0),
-        "up_proj": ("gate_up_proj", 1),
-    }
 
     # Gemma does not apply LoRA to the embedding layer.
     embedding_modules = {}