add missing norm topk bias

Author: CISC

src/llama-graph.cpp

@@ -981,6 +981,9 @@ ggml_tensor * llm_graph_context::build_moe_ffn(
         ggml_tensor * weights_sum = ggml_sum_rows(ctx0, weights); // [1, n_tokens]
         cb(weights_sum, "ffn_moe_weights_sum", il);
 
+        weights_sum = ggml_scale_bias(ctx0, weights_sum, 1.0, 1e-20);
+        cb(weights_sum, "ffn_moe_weights_sum_biased", il);
+
         weights = ggml_div(ctx0, weights, weights_sum); // [n_expert_used, n_tokens]
         cb(weights, "ffn_moe_weights_norm", il);