switched from fitpc/atom to prime/linux

Also removed a few old things that had nothing reasonable to be changed
to.
diff --git a/aos/common/mutex_test.cpp b/aos/common/mutex_test.cpp
index 652cd9e..29e1956 100644
--- a/aos/common/mutex_test.cpp
+++ b/aos/common/mutex_test.cpp
@@ -9,7 +9,7 @@
 
 #include "gtest/gtest.h"
 
-#include "aos/atom_code/ipc_lib/aos_sync.h"
+#include "aos/linux_code/ipc_lib/aos_sync.h"
 
 namespace aos {
 namespace testing {