PEL: Add enums for transmission states

So far, the states are new, sent, and acked.

Also added PEL object access to getting and setting these on the User
Header section object.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I0dfb2d1a39fe69b2a47bf7d461f08e92039a3e03
diff --git a/extensions/openpower-pels/pel_types.hpp b/extensions/openpower-pels/pel_types.hpp
index ae886eb..9a33ccf 100644
--- a/extensions/openpower-pels/pel_types.hpp
+++ b/extensions/openpower-pels/pel_types.hpp
@@ -119,5 +119,16 @@
     osHWErrorBit = 6                 // 0x0040
 };
 
+/**
+ * @brief The PEL transmission states
+ */
+enum class TransmissionState
+{
+    newPEL = 0,
+    badPEL = 1,
+    sent = 2,
+    acked = 3
+};
+
 } // namespace pels
 } // namespace openpower