[BugFix] skip language model in Encoder (#30242)

Signed-off-by: dengyunyang <584797741@qq.com>

vllm/model_executor/models/qwen2_5_vl.py

@@ -34,7 +34,7 @@ import einops
 import torch
 import torch.nn as nn
 import torch.nn.functional as F
-from transformers import BatchFeature
+from transformers import BatchFeature, Qwen2ForCausalLM
 from transformers.models.qwen2_5_vl import Qwen2_5_VLProcessor
 from transformers.models.qwen2_5_vl.configuration_qwen2_5_vl import (
     Qwen2_5_VLConfig,
@@ -1567,3 +1567,11 @@ class Qwen2_5_VLForConditionalGeneration(
             connector="visual.merger.",
             tower_model="visual.",
         )
+
+    @classmethod
+    def get_language_model_spec(cls) -> tuple[nn.Module | None, str | None]:
+        """
+        Return the language model spec:
+        (language model class, language model attr)
+        """
+        return Qwen2ForCausalLM, "language_model"