Update TRexTransport.java

Author: Emil-Gustafsson

src/main/java/com/cisco/trex/stateless/TRexTransport.java

@@ -10,6 +10,7 @@
 import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.zeromq.SocketType;
 import org.zeromq.ZMQ;
 import org.zeromq.ZMQException;