PEL: Move PEL section IDs into a header file

These will eventually need to be known to a piece of code that
unflattens a PEL into the appropriate section class objects based on the
section ID field in the PEL data.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I90b9d4be49b2e3807a620745fa663f94f7f4e62c
diff --git a/extensions/openpower-pels/private_header.cpp b/extensions/openpower-pels/private_header.cpp
index d4c3dee..fc62df1 100644
--- a/extensions/openpower-pels/private_header.cpp
+++ b/extensions/openpower-pels/private_header.cpp
@@ -1,5 +1,7 @@
 #include "private_header.hpp"
 
+#include "pel_types.hpp"
+
 #include <phosphor-logging/log.hpp>
 
 namespace openpower
@@ -28,7 +30,7 @@
 {
     bool failed = false;
 
-    if (header().id != privateHeaderSectionID)
+    if (header().id != static_cast<uint16_t>(SectionID::privateHeader))
     {
         log<level::ERR>("Invalid private header section ID",
                         entry("ID=0x%X", header().id));