face: move common declarations to face-common.hpp

Change-Id: I0e3e7a93f0693b0e24ca67493a4229987e792ef4
diff --git a/daemon/face/link-service.hpp b/daemon/face/link-service.hpp
index 8396137..415c185 100644
--- a/daemon/face/link-service.hpp
+++ b/daemon/face/link-service.hpp
@@ -26,15 +26,13 @@
 #ifndef NFD_DAEMON_FACE_LINK_SERVICE_HPP
 #define NFD_DAEMON_FACE_LINK_SERVICE_HPP
 
-#include "face-log.hpp"
+#include "face-common.hpp"
 #include "transport.hpp"
 #include "common/counter.hpp"
 
 namespace nfd {
 namespace face {
 
-class Face;
-
 /** \brief counters provided by LinkService
  *  \note The type name 'LinkServiceCounters' is implementation detail.
  *        Use 'LinkService::Counters' in public API.