Polish code

test=develop

paddle/fluid/framework/operator.cc

@@ -29,7 +29,6 @@ DECLARE_bool(benchmark);
 DEFINE_bool(check_nan_inf, false,
             "Checking whether operator produce NAN/INF or not. It will be "
             "extremely slow so please use this flag wisely.");
-DEFINE_int32(inner_op_parallelism, 0, "number of threads for inner op");
 
 namespace paddle {
 namespace framework {