[Refactor] Remove get_encoder_dummy_data (#32241)

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

vllm/model_executor/models/whisper.py

@@ -681,6 +681,10 @@ class WhisperProcessingInfo(BaseProcessingInfo):
     def get_hf_config(self) -> WhisperConfig:
         return self.ctx.get_hf_config(WhisperConfig)
 
+    @property
+    def skip_prompt_length_check(self) -> bool:
+        return True  # Because the encoder prompt is padded
+
     def get_supported_mm_limits(self) -> Mapping[str, int | None]:
         return {"audio": 1}
 
@@ -733,10 +737,6 @@ class WhisperMultiModalProcessor(EncDecMultiModalProcessor[WhisperProcessingInfo
             target_channels=self.info.get_target_channels(),
         )
 
-    @property
-    def pad_dummy_encoder_prompt(self) -> bool:
-        return True
-
     def create_encoder_prompt(
         self,
         prompt: str | list[int],