[Misc] clean up useless function (#3348)

Remove the interface which has been removed from vLLM already.
- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

vllm_ascend/platform.py

@@ -87,10 +87,6 @@ class NPUPlatform(Platform):
     def get_device_name(cls, device_id: int = 0) -> str:
         return torch.npu.get_device_name(device_id)
 
-    @classmethod
-    def is_async_output_supported(cls, enforce_eager: Optional[bool]) -> bool:
-        return True
-
     @classmethod
     def inference_mode(cls):
         return torch.inference_mode()
@@ -379,13 +375,6 @@ class NPUPlatform(Platform):
     def is_pin_memory_available(cls):
         return True
 
-    @classmethod
-    def supports_v1(cls, model_config: ModelConfig) -> bool:
-        """Returns whether the current platform can support v1 for the supplied
-        model configuration.
-        """
-        return True
-
     @classmethod
     def get_static_graph_wrapper_cls(cls) -> str:
         """