PEL: Make action flags optional in the registry

A future commit will fill in the field if it isn't
present.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I67371433162ce2198a362796d274695a1bd6a6dc
diff --git a/extensions/openpower-pels/registry.hpp b/extensions/openpower-pels/registry.hpp
index c55c624..d75c30a 100644
--- a/extensions/openpower-pels/registry.hpp
+++ b/extensions/openpower-pels/registry.hpp
@@ -99,7 +99,7 @@
     /**
      * @brief The PEL action flags field.
      */
-    uint16_t actionFlags;
+    std::optional<uint16_t> actionFlags;
 
     /**
      * @brief  The optional action flags to use instead when in manufacturing