core_timing: Split off utility functions into core_timing_util

src/core/hle/kernel/timer.cpp

@@ -6,6 +6,7 @@
 #include "common/assert.h"
 #include "common/logging/log.h"
 #include "core/core_timing.h"
+#include "core/core_timing_util.h"
 #include "core/hle/kernel/handle_table.h"
 #include "core/hle/kernel/kernel.h"
 #include "core/hle/kernel/thread.h"