[Feature] Support DeepSeek MTP on NPU (#11897)

Co-authored-by: liupeng374 <liupeng374@huawei.com>

python/sglang/srt/models/deepseek_nextn.py

@@ -38,12 +38,13 @@ from sglang.srt.models.deepseek_v2 import (
     enable_nextn_moe_bf16_cast_to_fp8,
 )
 from sglang.srt.server_args import get_global_server_args
-from sglang.srt.utils import BumpAllocator, add_prefix, is_cuda
+from sglang.srt.utils import BumpAllocator, add_prefix, is_cuda, is_npu
 
 logger = logging.getLogger(__name__)
 
 
 _is_cuda = is_cuda()
+_is_npu = is_npu()
 
 
 class DeepseekModelNextN(nn.Module):
@@ -85,13 +86,21 @@ class DeepseekModelNextN(nn.Module):
         self.eh_proj = nn.Linear(2 * config.hidden_size, config.hidden_size, bias=False)
 
         self.alt_stream = torch.cuda.Stream() if _is_cuda else None
+
+        layer_name = "decoder"
+        if _is_npu and (
+            get_global_server_args().speculative_draft_model_path
+            == get_global_server_args().model_path
+        ):
+            layer_name = "layers." + str(config.num_hidden_layers)
+
         self.decoder = DeepseekV2DecoderLayer(
             config,
             0,
             quant_config=quant_config,
             moe_quant_config=moe_quant_config,
             is_nextn=True,
-            prefix=add_prefix("decoder", prefix),
+            prefix=add_prefix(layer_name, prefix),
             alt_stream=self.alt_stream,
         )