Correct listener name

Author: tedyu

external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaTestUtils.scala

@@ -122,7 +122,7 @@ class KafkaTestUtils(withBrokerProps: Map[String, Object] = Map.empty) extends L
       brokerConf = new KafkaConfig(brokerConfiguration, doLog = false)
       server = new KafkaServer(brokerConf)
       server.startup()
-      brokerPort = server.boundPort(new ListenerName("CLIENT"))
+      brokerPort = server.boundPort(new ListenerName("PLAINTEXT"))
       (server, brokerPort)
     }, new SparkConf(), "KafkaBroker")