[2/4][Refactor] Refactor torchair utils (#1892)

There is a lot torchair specified logic in common code. It results hard
code maintenance. We will create a new torchair module to launch
torchair related logic there. I plan to add 4 PR.

1. Refactor worker
2. Refactor utils (this PR)
- simple change that move all torchair related util function to torchair
module
3. Refactor model_runner
4. Refactor attention

- vLLM version: v0.9.2
- vLLM main:
8188196a1c

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

vllm_ascend/attention/mla_v1.py

@@ -21,8 +21,8 @@ from vllm_ascend.multistream.base import MSAttentionMetadataSplitConfig
 from vllm_ascend.multistream.context import get_multistream_comm_context
 from vllm_ascend.multistream.ms_split import model_input_split_v1_mla_attn
 from vllm_ascend.ops.attention import vanilla_chunked_prefill_mla
-from vllm_ascend.utils import (npu_prefetch, npu_stream_switch,
-                               npu_wait_tensor, vllm_version_is)
+from vllm_ascend.torchair.utils import npu_stream_switch, npu_wait_tensor
+from vllm_ascend.utils import npu_prefetch, vllm_version_is
 from vllm_ascend.worker.npu_input_batch import InputBatch
 
 if TYPE_CHECKING: