update .clang-format

Added the header inclusion order to the .clang-format file generated
these changes.

Change-Id: I4f51a20f469de431ee6a5ba78e3f4da39c980fab
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/src/sdevent/timer.hpp b/src/sdevent/timer.hpp
index 5e45b94..405da4e 100644
--- a/src/sdevent/timer.hpp
+++ b/src/sdevent/timer.hpp
@@ -1,12 +1,13 @@
 #pragma once
 
+#include "sdevent/event.hpp"
+#include "sdevent/source.hpp"
+
+#include <systemd/sd-event.h>
+
 #include <chrono>
 #include <functional>
 #include <memory>
-#include <systemd/sd-event.h>
-
-#include "sdevent/source.hpp"
-#include "sdevent/event.hpp"
 
 // TODO: openbmc/openbmc#1720 - add error handling for sd_event API failures