Fix checkstyle issue

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/security/OzoneTokenIdentifier.java

@@ -29,7 +29,6 @@ import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.OMTokenProto;
 import org.apache.hadoop.security.token.delegation.AbstractDelegationTokenIdentifier;
-import org.apache.hadoop.security.token.Token;
 
 /**
  * The token identifier for Ozone Master.