log uncaught Exception

- Use execute instead of submit so that uncaught Exception will
  be dealt and logged by ExecutorService's handler.
- Use component's own logger

Change-Id: I761264aea00748980929b5048e111756776dd2f6
diff --git a/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2GroupHandler.java b/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2GroupHandler.java
index a9c2bb1..2d3022d 100644
--- a/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2GroupHandler.java
+++ b/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2GroupHandler.java
@@ -117,7 +117,7 @@
     private Cache<GroupKey, List<OfdpaNextGroup>> pendingNextObjectives;
     private ConcurrentHashMap<GroupKey, Set<GroupChainElem>> pendingGroups;
     private ScheduledExecutorService groupChecker =
-            Executors.newScheduledThreadPool(2, groupedThreads("onos/pipeliner", "ofdpa2-%d"));
+            Executors.newScheduledThreadPool(2, groupedThreads("onos/pipeliner", "ofdpa2-%d", log));
 
     // index number for group creation
     private AtomicCounter nextIndex;