Fix import of logging macro.

Author: achan1989

src/generate/peripheral.rs

@@ -5,6 +5,7 @@ use either::Either;
 use quote::{ToTokens, Tokens};
 use crate::svd::{Cluster, ClusterInfo, Defaults, Peripheral, Register};
 use syn::{self, Ident};
+use log::warn;
 
 use crate::errors::*;
 use crate::util::{self, ToSanitizedSnakeCase, ToSanitizedUpperCase, BITS_PER_BYTE};