[Bugfix] Fix MoeWNA16Method activation (#14024)

Author: jeejeelee

vllm/model_executor/layers/quantization/moe_wna16.py

@@ -293,9 +293,10 @@ def apply(
         custom_routing_function: Optional[Callable] = None,
         scoring_func: str = "softmax",
         e_score_correction_bias: Optional[torch.Tensor] = None,
+        activation: str = "silu",
     ) -> torch.Tensor:
         from vllm.model_executor.layers.fused_moe import fused_experts
-
+        assert activation == "silu", "Only SiLU activation is supported."
         topk_weights, topk_ids = FusedMoE.select_experts(
             hidden_states=x,
             router_logits=router_logits,