Remove multiple logging implementations.

Change-Id: I7474c29b394f37918a35bba58b2fab58a7be930f
diff --git a/aos/logging/log_displayer.cc b/aos/logging/log_displayer.cc
index d3e5728..fa8fe6b 100644
--- a/aos/logging/log_displayer.cc
+++ b/aos/logging/log_displayer.cc
@@ -154,7 +154,7 @@
   int32_t source_pid = -1;
 
   ::aos::logging::Init();
-  ::aos::logging::AddImplementation(
+  ::aos::logging::SetImplementation(
       new ::aos::logging::StreamLogImplementation(stdout));
 
   while (true) {