[Spec Decode, BugFix] Propagate norm_before_fc from Eagle3 speculator (vllm-project#38111)

Signed-off-by: Shubhra Pandit <shubhra.pandit@gmail.com>

Author: shubhra

vllm/transformers_utils/configs/speculators/algos.py

@@ -22,6 +22,7 @@ def update_eagle3(config_dict: dict, pre_trained_config: dict) -> None:
     - draft_vocab_size: Size of the draft model's vocabulary
     - target_hidden_size: Hidden size of the target model
     - norm_before_residual: Whether to apply norm before residual connection
+    - norm_before_fc: Whether to apply RMSNorm before the fc projection
     - eagle_aux_hidden_state_layer_ids: List of layer indices from the base
         model to use as auxiliary inputs for the Eagle3 drafter. These layers
         provide intermediate hidden states that help the drafter make better
@@ -34,6 +35,7 @@ def update_eagle3(config_dict: dict, pre_trained_config: dict) -> None:
     pre_trained_config["norm_before_residual"] = config_dict.get(
         "norm_before_residual", True
     )
+    pre_trained_config["norm_before_fc"] = config_dict.get("norm_before_fc", False)
     pre_trained_config["architectures"] = ["Eagle3LlamaForCausalLM"]
     if config_dict.get("eagle_aux_hidden_state_layer_ids"):
         pre_trained_config["eagle_aux_hidden_state_layer_ids"] = config_dict[