Increase port count for switch added test in LinkDiscoveryManagerTest

to account for the fact that the quarantine port processing rate has
increased from 5 ports/100 msec to 10 ports/100 msec

src/test/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManagerTest.java

@@ -468,7 +468,7 @@ public class LinkDiscoveryManagerTest extends FloodlightTestCase {
 
         // Create the set of ports
         List<Short> ports = new ArrayList<Short>();
-        for(short p=1; p<=10; ++p) {
+        for(short p=1; p<=20; ++p) {
             ports.add(p);
         }