assign n_batch value to n_ubatch

examples/retrieval/retrieval.cpp

@@ -108,6 +108,9 @@ int main(int argc, char ** argv) {
         return 1;
     }
 
+    // For BERT models, batch size must be equal to ubatch size
+    params.n_ubatch = params.n_batch;
+
     if (params.chunk_size <= 0) {
         fprintf(stderr, "chunk_size must be positive\n");
         return 1;