misc: net_util: drop extern crate, use modern rust

This commit is part of a series of similar commits.

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

net_util/src/mac.rs

@@ -8,6 +8,7 @@
 use std::str::FromStr;
 use std::{fmt, io};
 
+use log::error;
 use serde::de::{Deserialize, Deserializer, Error};
 use serde::ser::{Serialize, Serializer};