[feat]decode convert bsnd to tnd and fix bug when pcp and dcp (#3980)

### What this PR does / why we need it?
1、in attention_v1 module, convert bsnd t0 tnd when pcp and dcp
2、fix tochair bug: service startup problem

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: v0.11.0
- vLLM main:
83f478bb19

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

vllm_ascend/worker/model_runner_v1.py

@@ -1411,11 +1411,14 @@ class NPUModelRunner(LoRAModelRunnerMixin):
             req_indices, positions_np)
         self.input_batch.block_table.commit_slot_mapping(
             total_num_scheduled_tokens)
-        tokens, position_pcp, pcp_unpad_mask = self._update_tokens_for_pcp(
-            tokens)
-        num_scheduled_tokens = np.array(tokens, dtype=np.int32)
-        # update total_num_scheduled_tokens
-        total_num_scheduled_tokens = sum(num_scheduled_tokens[:num_reqs])
+        if self.pcp_size > 1:
+            tokens, position_pcp, pcp_unpad_mask = self._update_tokens_for_pcp(
+                tokens)
+            num_scheduled_tokens = np.array(tokens, dtype=np.int32)
+            total_num_scheduled_tokens = sum(num_scheduled_tokens[:num_reqs])
+        else:
+            position_pcp, pcp_unpad_mask = None, None
+            self.num_pcp_pads = self.num_pcp_pads[:num_reqs]
 
         total_num_pcp_pads = sum(self.num_pcp_pads)
         max_num_scheduled_tokens = max(tokens)
@@ -4180,8 +4183,6 @@ class NPUModelRunner(LoRAModelRunnerMixin):
     def _update_tokens_for_pcp(self, tokens):
         num_reqs = self.input_batch.num_reqs
         self.num_pcp_pads = self.num_pcp_pads[:num_reqs]
-        if not self.pcp_size > 1:
-            return tokens, None, None
         tokens = np.array(tokens, dtype=np.int32)
         num_decode_reqs = sum(
             self.input_batch.num_computed_tokens_cpu[:num_reqs] >=