Add missing dependency in AWSIotMqttManager

Author: Karthikeyan

aws-android-sdk-iot/src/main/java/com/amazonaws/mobileconnectors/iot/AWSIotMqttManager.java

@@ -47,6 +47,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Map;
 
 import javax.net.SocketFactory;