[Platform] add dispatch key

Signed-off-by: MengqingCao <cmq0113@163.com>

Author: MengqingCao

vllm_ascend/platform.py

@@ -52,6 +52,7 @@ class NPUPlatform(Platform):
     simple_compile_backend: str = "npu"
     ray_device_key: str = "NPU"
     device_control_env_var: str = "ASCEND_RT_VISIBLE_DEVICES"
+    dispatch_key: str = "NPU"
 
     @classmethod
     def get_device_capability(cls, device_id: int = 0):