Clean up unused padding_idx variables across many model definitions (#13240)

Signed-off-by: Tyler Michael Smith <tyler@neuralmagic.com>

vllm/model_executor/models/whisper.py

@@ -49,10 +49,7 @@ class WhisperAudioInputs(TypedDict):
 
 class WhisperPositionalEmbedding(nn.Embedding):
 
-    def __init__(self,
-                 num_positions: int,
-                 embedding_dim: int,
-                 padding_idx: Optional[int] = None):
+    def __init__(self, num_positions: int, embedding_dim: int):
         super().__init__(num_positions, embedding_dim)
 
     def forward(self, position_ids):
@@ -359,7 +356,6 @@ class WhisperEncoder(nn.Module):
         config = vllm_config.model_config.hf_config
         embed_dim = config.d_model
         self.num_mel_bins = config.num_mel_bins
-        self.padding_idx = config.pad_token_id
         self.max_source_positions = config.max_source_positions
         self.embed_scale = (math.sqrt(embed_dim)
                             if config.scale_embedding else 1.0)