mgmt: expose link layer counters in Face Dataset

refs #1767

Change-Id: If0b66ead4c2f2741c83396f251cce9a0d83c1520
diff --git a/daemon/face/face.cpp b/daemon/face/face.cpp
index 4197aa5..385f0a9 100644
--- a/daemon/face/face.cpp
+++ b/daemon/face/face.cpp
@@ -128,17 +128,13 @@
 ndn::nfd::FaceStatus
 Face::getFaceStatus() const
 {
-  const FaceCounters& counters = getCounters();
-
   ndn::nfd::FaceStatus status;
   status.setFaceId(getId())
     .setRemoteUri(getRemoteUri().toString())
     .setLocalUri(getLocalUri().toString())
-    .setFlags(getFaceFlags(*this))
-    .setNInInterests(counters.getNInInterests())
-    .setNInDatas(counters.getNInDatas())
-    .setNOutInterests(counters.getNOutInterests())
-    .setNOutDatas(counters.getNOutDatas());
+    .setFlags(getFaceFlags(*this));
+
+  this->getCounters().copyTo(status);
 
   return status;
 }