[Model] Implement missing `get_language_model` for Keye-VL (#20631)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/model_executor/models/keye.py

@@ -1592,6 +1592,9 @@ class KeyeForConditionalGeneration(nn.Module, SupportsMultiModal, SupportsLoRA,
 
         return modalities
 
+    def get_language_model(self) -> torch.nn.Module:
+        return self.language_model
+
     def get_multimodal_embeddings(
             self, **kwargs: object) -> Optional[MultiModalEmbeddings]: