Revert "Fix doxygen error"

This reverts commit d175d524330d4df2292bcbfa459562cb45558ee4.

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/constant_flow.h b/library/constant_flow.h
index 9554cfc..ff464e6 100644
--- a/library/constant_flow.h
+++ b/library/constant_flow.h
@@ -26,7 +26,7 @@
 
 #include "mbedtls/build_info.h"
 
-/**
+/*
  * This file defines the two macros
  *
  *  #define TEST_CF_SECRET(ptr, size)