[BugFix] add logic when KVCacheSpec group has compress ratio > 1 (vllm-project#10865)

### What this PR does / why we need it?

DeepSeek-V4-Flash or self_attn and indexer_k_cache group (when
compress_ratio=4) max_num_block_per_req changing incorrect because
```py
if (kv_cache_group is not None
    and hasattr(kv_cache_group, "kv_cache_spec")
    and hasattr(kv_cache_group.kv_cache_spec, "compress_ratio")
     ):
         compress_ratio = kv_cache_group.kv_cache_spec.compress_ratio
```
is unreachable. I changed the logic.

- vLLM version: v0.22.1
- vLLM main:
vllm-project/vllm@967c5c3
---------
Signed-off-by: KlyzhenkoVadim <vadimklyzhenko@gmail.com>
Signed-off-by: Vadim <87440656+KlyzhenkoVadim@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: KlyzhenkoVadim

vllm_ascend/worker/block_table.py

@@ -3,7 +3,7 @@
 from vllm.distributed import get_dcp_group, get_pcp_group
 from vllm.utils.math_utils import cdiv
 from vllm.v1.attention.backends.utils import PAD_SLOT_ID
-from vllm.v1.kv_cache_interface import KVCacheGroupSpec, MambaSpec
+from vllm.v1.kv_cache_interface import KVCacheGroupSpec, MambaSpec, UniformTypeKVCacheSpecs
 from vllm.v1.utils import CpuGpuBuffer
 from vllm.v1.worker.block_table import _compute_slot_mapping_kernel
 from vllm.v1.worker.cp_utils import get_total_cp_world_size
@@ -32,9 +32,11 @@ def __init__(
         if (
             kv_cache_group is not None
             and hasattr(kv_cache_group, "kv_cache_spec")
-            and hasattr(kv_cache_group.kv_cache_spec, "compress_ratio")
+            and isinstance(kv_cache_group.kv_cache_spec, UniformTypeKVCacheSpecs)
         ):
-            compress_ratio = kv_cache_group.kv_cache_spec.compress_ratio
+            kv_cache_spec = next(iter(kv_cache_group.kv_cache_spec.kv_cache_specs.values()), None)
+            if kv_cache_spec is not None and hasattr(kv_cache_spec, "compress_ratio"):
+                compress_ratio = kv_cache_spec.compress_ratio
         if (
             kv_cache_group is not None
             and hasattr(kv_cache_group, "kv_cache_spec")