remove redundant params in mla_preprocess kernel (#3530)

### What this PR does / why we need it?

This pull request removes the redundant parameters `gamma1` and `beta1`
(also named `gamma0`/`beta0` in some places) from the `mla_preprocess`
kernel and its calling hierarchy. The changes are consistent across C++
kernel code, bindings, and Python call sites. The parameters were unused
in the lower-level functions, so their removal is a good cleanup.

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

The python interface of the kernel is affected, and the params of
`gamma0` and `beta0` are not needed.

### How was this patch tested?

The unit-test of the kernel is adapted accordingly.


- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

Signed-off-by: mojave2 <chenchen145@huawei.com>

tests/e2e/singlecard/ops/test_mla_preprocess.py

@@ -18,8 +18,6 @@ def test_mla_preprocess_kernel():
     dtype = torch.bfloat16
 
     hidden_states = torch.randn((token_num, N_7168), dtype=dtype).npu()
-    gamma0 = torch.randn((N_7168), dtype=dtype).npu()
-    beta0 = torch.randn((N_7168), dtype=dtype).npu()
     quant_scale0 = torch.randn((1, ), dtype=dtype).npu()
     quant_offset0 = torch.randint(0, 7, (1, ), dtype=torch.int8).npu()
 
@@ -74,8 +72,6 @@ def test_mla_preprocess_kernel():
 
     torch.ops._C_ascend.mla_preprocess(
         hidden_states,
-        gamma0,
-        beta0,
         wdqkv,
         de_scale0,
         gamma1,

tests/e2e/singlecard/spec_decode_v1/test_v1_mtp_correctness.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+import os
+from unittest.mock import patch
+
 import pytest
 from vllm import SamplingParams
 from vllm.config import CompilationConfig, CUDAGraphMode
@@ -108,3 +111,19 @@ def test_mtp2_correctness_full_graph(
     model_name: str,
 ):
     mtp_correctness(sampling_config, model_name, 2, CUDAGraphMode.FULL)
+
+
+@patch.dict(os.environ, {"VLLM_ASCEND_ENABLE_MLAPO": "1"})
+def test_mtp_correctness_piecewise_graph_with_mlapo_kernel(
+    sampling_config: SamplingParams,
+    model_name: str,
+):
+    mtp_correctness(sampling_config, model_name, 1)
+
+
+@patch.dict(os.environ, {"VLLM_ASCEND_ENABLE_MLAPO": "1"})
+def test_mtp_correctness_full_graph_with_mlapo_kernel(
+    sampling_config: SamplingParams,
+    model_name: str,
+):
+    mtp_correctness(sampling_config, model_name, 1, CUDAGraphMode.FULL)