Adding a component config to take down single homed host ports when all uplinks are lost.

In addition:
   - handle port updates that may be lost if mastership changes at same time
   - fix javadoc in DeviceService

Change-Id: I032909e8ab9564cf9c978b1d66abd3ab32c814d7
diff --git a/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java b/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java
index 0282fa4..626109a 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java
@@ -725,4 +725,7 @@
         }
     }
 
+    public boolean isPairLocalPort(DeviceId devId, PortNumber pnum) {
+        return pnum.equals(srManager.getPairLocalPort(devId).orElse(null));
+    }
 }