Fix issues found by FindBugs: ICAST_INTEGER_MULTIPLY_CAST_TO_LONG

http://findbugs.sourceforge.net/bugDescriptions.html#ICAST_INTEGER_MULTIPLY_CAST_TO_LONG

For some reason, initially FindBugs reported only a single
ICAST_INTEGER_MULTIPLY_CAST_TO_LONG issue within this file (fixed earlier).
After this issue was fixed, FindBugs reported another issue (fixed in
this patch).

Change-Id: I9321a9d89967afcd2e0548560dfc6acc60530ee7
diff --git a/src/main/java/net/onrc/onos/core/linkdiscovery/internal/LinkDiscoveryManager.java b/src/main/java/net/onrc/onos/core/linkdiscovery/internal/LinkDiscoveryManager.java
index adcacd8..7989aaa 100644
--- a/src/main/java/net/onrc/onos/core/linkdiscovery/internal/LinkDiscoveryManager.java
+++ b/src/main/java/net/onrc/onos/core/linkdiscovery/internal/LinkDiscoveryManager.java
@@ -1523,7 +1523,7 @@
                     linkChanged = true;
                 }
                 if ((info.getMulticastValidTime() != null) &&
-                        (info.getMulticastValidTime() + (this.LINK_TIMEOUT * 1000) < curTime)) {
+                        (info.getMulticastValidTime() + (1000L * this.LINK_TIMEOUT) < curTime)) {
                     info.setMulticastValidTime(null);
                     // if uTime is not null, then link will remain as openflow
                     // link. If uTime is null, it will be deleted.  So, we