Remove two unnecessary imports

The wire module exports std::io::Read now.

dns/src/record/a.rs

@@ -1,4 +1,3 @@
-use std::io::Read;
 use std::net::Ipv4Addr;
 
 use log::*;

dns/src/record/aaaa.rs

@@ -1,4 +1,3 @@
-use std::io::Read;
 use std::net::Ipv6Addr;
 
 use log::*;