[Bugfix] Correct method call for _set_cos_sin_cache (#774)

This change ensures proper functionality for longer sequences by
correctly invoking the _set_cos_sin_cache method with self as the first
argument.

For example, with DeepSeek R1, if this change isn't made, the program
will crash when the input sequence exceeds 4096.

Signed-off-by: Jade Zheng <zheng.shoujian@outlook.com>

vllm_ascend/ops/rotary_embedding.py

@@ -82,7 +82,7 @@ def native_rope_deepseek_forward(self,
                                  offsets: Optional[torch.Tensor] = None,
                                  max_seq_len: Optional[int] = None):
     if max_seq_len is not None and max_seq_len > self.max_seq_len:
-        self._set_cos_sin_cache(max_seq_len, query.device, query.dtype)
+        _set_cos_sin_cache(self, max_seq_len, query.device, query.dtype)
     if len(key.shape) == 2:
         key = key[:, None, :]
     # Note: we implement the non neox_style method with shuffle the last dim and neox style