[Bugfix] fix pcp + eplb error (#5561)

### What this PR does / why we need it?
Fix the bug in the PCP overlay feature

1、Fix the bug related to PCP and EPLB overlap by including PCP size in
the word_size calculation.
2、In the PCP pooling scenario, a prompt has been added for setting the
cp_kv_cache_interleave_size.

- vLLM version: v0.13.0
- vLLM main:
7157596103

Signed-off-by: weiguihua2 <weiguihua2@huawei.com>

vllm_ascend/patch/platform/patch_multiproc_executor.py

@@ -36,10 +36,12 @@ class AscendMultiprocExecutor(MultiprocExecutor):
         self.local_world_size = self.parallel_config.local_world_size
         tensor_parallel_size = self.parallel_config.tensor_parallel_size
         pp_parallel_size = self.parallel_config.pipeline_parallel_size
-        assert self.world_size == tensor_parallel_size * pp_parallel_size, (
+        pcp_parallel_size = self.parallel_config.prefill_context_parallel_size
+        assert self.world_size == tensor_parallel_size * pp_parallel_size * pcp_parallel_size, (
             f"world_size ({self.world_size}) must be equal to the "
             f"tensor_parallel_size ({tensor_parallel_size}) x pipeline"
-            f"_parallel_size ({pp_parallel_size}). ")
+            f"_parallel_size ({pp_parallel_size}) x prefill_context"
+            f"_parallel_size ({pcp_parallel_size}). ")
 
         # Set multiprocessing envs
         set_multiprocessing_worker_envs()