[Model][3/N] Refactor sfa into mla and remove deepseek_v3_2.py (#3769)

This is the follow-up PR to PR #3189, which continues to refactor sfa
into mla and finally remove deepseek_v3_2.py. This is the last PR of
deepseek modeling refactoring. After this, all deepseek-related model
codes are removed from vllm_ascend.

FurtherMore, after this PR deepseek v3.2 can run chunk-prefill with
correct accuracy.

- vLLM version: v0.11.0rc3
- vLLM main:
83f478bb19

---------

Signed-off-by: whx-sjtu <2952154980@qq.com>

vllm_ascend/models/__init__.py

@@ -29,10 +29,6 @@ def register_model():
             "vllm_ascend.models.qwen2_5_vl_without_padding:AscendQwen2_5_VLForConditionalGeneration_Without_Padding"
         )
 
-    ModelRegistry.register_model(
-        "DeepseekV32ForCausalLM",
-        "vllm_ascend.models.deepseek_v3_2:CustomDeepseekV3ForCausalLM")
-
     # There is no PanguProMoEForCausalLM in vLLM, so we should register it before vLLM config initialization
     # to make sure the model can be loaded correctly. This register step can be removed once vLLM support PanguProMoEForCausalLM.
     ModelRegistry.register_model(