[Model] Add support for H2OVL-Mississippi models (#9747)

Signed-off-by: Shanshan Wang <shanshan.wang@h2o.ai>
Signed-off-by: Roger Wang <ywang@roblox.com>
Co-authored-by: Roger Wang <ywang@roblox.com>

vllm/entrypoints/chat_utils.py

@@ -187,7 +187,8 @@ class BaseMultiModalItemTracker(ABC, Generic[_T]):
             if model_type.startswith("llava"):
                 return self._cached_token_str(self._tokenizer,
                                               hf_config.image_token_index)
-            if model_type in ("chameleon", "internvl_chat", "NVLM_D"):
+            if model_type in ("chameleon", "internvl_chat", "NVLM_D",
+                              "h2ovl_chat"):
                 return "<image>"
             if model_type == "mllama":
                 return "<|image|>"