fix nullptr block in op_teller (#36622)

paddle/fluid/framework/ir/quant_conv2d_dequant_fuse_pass.cc

@@ -548,7 +548,8 @@ void QuantDequantFusePass::FuseDequant(ir::Graph* graph, Scope* scope,
     std::string new_input = quantized_op_input_node->Name();
     std::string new_output = dequant_op_out_node->Name();
 
-    framework::OpDesc new_op_desc(base_op_desc, nullptr);
+    framework::OpDesc new_op_desc(base_op_desc,
+                                  quantized_op_node->Op()->Block());
     new_op_desc.SetType(quantized_op_type);
     new_op_desc.SetAttr("enable_int8", true);
     if (quantized_op_type == "conv2d" || quantized_op_type == "conv2d_fusion" ||