fix the checkstyle

Author: maoling

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/HQuorumPeer.java

@@ -23,7 +23,6 @@
 import java.io.PrintWriter;
 import java.net.InetAddress;
 import java.net.NetworkInterface;
-import java.net.UnknownHostException;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Enumeration;