【feat】switch for fusion ops gmmswigluquant (#5992)

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

Set a additional config parameter to control whether the gmmswigluequant
fuseion operator is enabled; it is enabled by True. / When enabled with
a small number of GPUs, the gmmswigluquant fused operator can cause some
performance degradation.

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

### How was this patch tested?

- vLLM version: v0.13.0
- vLLM main:
2c24bc6996

#### Perf

test model: GLM 4.6(w8a8)
- single A3 node(ep16, tp16),  async-scheduling, mtp, FULL_DECODE_ONLY
- bs=1, input_lens=32000, ouput_lens=1024

Without this PR: TPOT 32.22.ms
With this PR: TPOT 30.23ms

---------

Signed-off-by: zjks98 <zhangjiakang4@huawei.com>
Co-authored-by: zjks98 <zhangjiakang4@huawei.com>

vllm_ascend/platform.py

@@ -206,6 +206,13 @@ class NPUPlatform(Platform):
 
         elif model_config and hasattr(model_config.hf_text_config, "index_topk"):
             vllm_config.cache_config.cache_dtype = str(model_config.dtype).replace("torch.", "")
+
+        ascend_fusion_config = ascend_config.ascend_fusion_config
+        if ascend_fusion_config:
+            vllm_config.additional_config.setdefault("ascend_fusion_config", {}).update(
+                vars(ascend_fusion_config) if not isinstance(ascend_fusion_config, dict) else ascend_fusion_config
+            )
+
         if model_config is None:
             logger.warning("Model config is missing. This may indicate that we are running a test case")
             enforce_eager = False