[Deprecation] Remove `_get_data_parser` in MM processor (#33757)

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

vllm/multimodal/processing/processor.py

@@ -988,15 +988,14 @@ class BaseMultiModalProcessor(ABC, Generic[_I]):
         self.dummy_inputs = dummy_inputs
         self.cache = cache
 
+        # TODO: Remove in v0.18
         if hasattr(self, "_get_data_parser"):
-            logger.warning_once(
-                "BaseMultiModalProcessor._get_data_parser is deprecated "
-                "and will be removed in v0.16."
-                "You should override `info.build_data_parser` instead."
+            raise ValueError(
+                "BaseMultiModalProcessor._get_data_parser has been "
+                "moved to `BaseProcessingInfo.build_data_parser` in v0.16. "
+                "You should override `BaseProcessingInfo.build_data_parser` instead."
             )
 
-            self.data_parser = self._get_data_parser()  # type: ignore
-        else:
         self.data_parser = self.info.get_data_parser()
 
     @property