misc: devices: 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

devices/src/debug_console.rs

@@ -9,6 +9,7 @@ use std::io;
 use std::io::Write;
 use std::sync::{Arc, Barrier};
 
+use log::error;
 use vm_device::BusDevice;
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};