[BugFix] Fixes Qwen3-Next enable nz accuracy problem (#4058)

### What this PR does / why we need it?
- Fixes Qwen3-Next enable nz accuracy problem

### Does this PR introduce _any_ user-facing change?
N/A


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

---------

Signed-off-by: Icey <1790571317@qq.com>
Signed-off-by: wxsIcey <1790571317@qq.com>

tests/ut/attention/test_mla_v1.py

@@ -416,6 +416,7 @@ class TestAscendMLAImpl(TestBase):
         self.assertEqual(q_pe.shape[1], self.impl.num_heads)
         self.assertEqual(q_pe.shape[2], self.impl.qk_rope_head_dim)
 
+    @patch('vllm_ascend.utils._ENABLE_NZ', True)
     @patch('torch_npu.npu_format_cast')
     def test_process_weights_after_loading(self, mock_format_cast):
         layer = MagicMock(spec=LinearBase)