[bugfix] solve dp scenario Host-Device sync (#5298)

### What this PR does / why we need it?
In the speculative decoding scenario, the original code performs
Host-Device synchronization, which slows down the main model's execution
speed.

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

### How was this patch tested?

- vLLM version: release/v0.13.0
- vLLM main:
ad32e3e19c

Signed-off-by: hwhaokun <haokun0405@163.com>
Co-authored-by: realliujiaxu <realliujiaxu@163.com>

vllm_ascend/worker/model_runner_v1.py

@@ -1863,10 +1863,11 @@ class NPUModelRunner(GPUModelRunner):
                 # QUESTION: Why do we separately set query_start_loc for spec in the first place?
                 # While in _prepare_inputs we don't?
                 if self.speculative_config:
-                    self.query_start_loc.gpu[:num_reqs + 1] = torch.tensor(
+                    self.query_start_loc.cpu[:num_reqs + 1] = torch.tensor(
                         [0] + self.actual_seq_lengths_q[:num_reqs],
-                        device=self.device,
+                        device="cpu",
                         dtype=torch.int32)
+                    self.query_start_loc.copy_to_gpu()
                 common_attn_metadata = AscendCommonAttentionMetadata(
                     query_start_loc=self.query_start_loc.gpu[:num_reqs + 1],
                     query_start_loc_cpu=self.query_start_loc.cpu[:num_reqs +