misc: pci: 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

pci/src/bus.rs

@@ -10,6 +10,7 @@ use std::ops::DerefMut;
 use std::sync::{Arc, Barrier, Mutex};
 
 use byteorder::{ByteOrder, LittleEndian};
+use log::error;
 use thiserror::Error;
 use vm_device::{Bus, BusDevice, BusDeviceSync};