[Misc] Remove unused code from `protocol.py` (#29616)

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

vllm/engine/protocol.py

 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
-import enum
 from abc import ABC, abstractmethod
 from collections.abc import AsyncGenerator, Iterable, Mapping
 from typing import Any
 
 from vllm.config import ModelConfig, VllmConfig
 from vllm.inputs.data import PromptType
-from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
 from vllm.outputs import PoolingRequestOutput, RequestOutput
 from vllm.plugins.io_processors import IOProcessor
@@ -19,13 +17,6 @@ from vllm.transformers_utils.tokenizer import AnyTokenizer
 from vllm.v1.engine import EngineCoreRequest
 from vllm.v1.engine.processor import Processor
 
-logger = init_logger(__name__)
-
-
-class Device(enum.Enum):
-    GPU = enum.auto()
-    CPU = enum.auto()
-
 
 class EngineClient(ABC):
     """Protocol class for Clients to Engine"""