face: downgrade "Creating transport" log message to DEBUG

FaceTable already logs at INFO level whenever a new face is added.

Change-Id: Id2905c8b6d42df8bfc4c43cc12d432d9ce180aae
diff --git a/daemon/face/unicast-udp-transport.cpp b/daemon/face/unicast-udp-transport.cpp
index c872c09..c2c0d2b 100644
--- a/daemon/face/unicast-udp-transport.cpp
+++ b/daemon/face/unicast-udp-transport.cpp
@@ -60,7 +60,7 @@
   }
   BOOST_ASSERT(this->getMtu() >= MIN_MTU);
 
-  NFD_LOG_FACE_INFO("Creating transport");
+  NFD_LOG_FACE_DEBUG("Creating transport");
 
 #ifdef __linux__
   //