misc: vmm: 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

vmm/src/config.rs

@@ -11,6 +11,7 @@ use std::result;
 use std::str::FromStr;
 
 use clap::ArgMatches;
+use log::{debug, warn};
 use option_parser::{
     ByteSized, IntegerList, OptionParser, OptionParserError, StringList, Toggle, Tuple,
 };