build: Address issues found by 1.43.0 clippy

These are mostly due to use of "bare use" statements and unnecessary vector
creation.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

pci/src/bus.rs

@@ -8,7 +8,6 @@ use crate::configuration::{
 use crate::device::{DeviceRelocation, Error as PciDeviceError, PciDevice};
 use byteorder::{ByteOrder, LittleEndian};
 use devices::BusDevice;
-use std;
 use std::any::Any;
 use std::collections::HashMap;
 use std::ops::DerefMut;