[MM][Bugfix] Add error log for VL models when enabling FLASHCOMM (#4222)

### What this PR does / why we need it?

Add error log for VL models when enabling
`VLLM_ASCEND_ENABLE_FLASHCOMM1=1` or `VLLM_ASCEND_ENABLE_FLASHCOMM=1`
(for backward compatibility).

This is a temporary fix for
https://github.com/vllm-project/vllm-ascend/issues/4132.

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

Signed-off-by: shen-shanshan <467638484@qq.com>

vllm_ascend/utils.py

@@ -57,6 +57,7 @@ _ASCEND_CUSTOMOP_IS_REIGISTERED = False
 _DEFAULT_BUFFER_SIZE = 200
 _MIN_DP_BUFFER_SIZE = 50
 _IS_MOE_MODEL = None
+_IS_VL_MODEL = None
 _ENABLE_SP = None
 _HAS_LAYER_IDX = None
 _ENABLE_NZ = None
@@ -696,6 +697,15 @@ def _is_contain_expert(config: Any):
     return False
 
 
+def is_vl_model(vllm_config: VllmConfig):
+    """Checks if the model is a VL model by config"""
+    global _IS_VL_MODEL
+    if _IS_VL_MODEL is None:
+        model_configs = vllm_config.model_config.hf_config.to_dict()
+        _IS_VL_MODEL = "VL" in model_configs["architectures"][0]
+    return _IS_VL_MODEL
+
+
 def weak_ref_tensor(tensor: Any) -> Any:
     """
     Create a weak reference to a tensor.