llama : deci : support ffn-free with attention (#13296)

Author: CISC

src/llama-model.cpp

@@ -4792,7 +4792,7 @@ struct llm_build_deci : public llm_graph_context {
             }
 
             // FFN-free layer of Llama-3_1-Nemotron-Ultra-253B
-            if (n_head == 0 && n_ff == 0) {
+            if (n_ff == 0) {
                 continue;
             }