[Model] Pass param prefix to LLMHead (#24862)

Signed-off-by: whx-sjtu <2952154980@qq.com>

vllm/model_executor/models/mamba2.py

@@ -278,6 +278,7 @@ class Mamba2ForCausalLM(nn.Module, HasInnerState, IsAttentionFree):
             # We need bigger padding if using lora for kernel
             # compatibility
             if not lora_config else lora_config.lora_vocab_padding_size,
+            prefix=maybe_prefix(prefix, "lm_head"),
         )
         if config.tie_word_embeddings:
             self.lm_head = self.lm_head.tie_weights(self.backbone.embeddings)