[Misc] remove unused file (cache.py) (#2377)

### What this PR does / why we need it?
cache.py only contains a function that will never be called, so remove
it.

### Does this PR introduce _any_ user-facing change?
No

- vLLM version: v0.10.0
- vLLM main:
f1f0d2fab8

Signed-off-by: 22dimensions <waitingwind@foxmail.com>

vllm_ascend/ops/cache.py

@@ -1,35 +0,0 @@
-# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
-# This file is a part of the vllm-ascend project.
-# Adapted from vllm/tests/kernels/test_moe.py
-# Copyright 2023 The vLLM team.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-import torch
-
-
-def concat_and_cache_mla(
-        kv_c_normed: torch.Tensor,  # [num_tokens, num_kv_head, nope]
-        k_pe: torch.Tensor,  # [num_tokens, num_kv_head, rope]
-        kv_cache: torch.
-    Tensor,  # [num_blocks, block_size, num_kv_head, nope + rope]
-        slot_mapping,  # [num_tokens]
-):
-    num_blocks = kv_cache.size()[0]
-    block_size = kv_cache.size()[1]
-    num_kv_head = k_pe.size()[1]
-
-    idx_for_copy = slot_mapping // block_size * block_size + slot_mapping % block_size
-    kv_cache = kv_cache.view(num_blocks * block_size, num_kv_head, -1)
-    kv_cache[idx_for_copy] = torch.cat([kv_c_normed.unsqueeze(1), k_pe],
-                                       dim=-1)