Update header includes for ported src/register/ code

Signed-off-by: Zane Shelley <zshelle@us.ibm.com>
Change-Id: I8a56d8119549717f96ae49eb1c1ba8d041e04914
diff --git a/src/register/prdfRegisterCache.C b/src/register/prdfRegisterCache.C
index e7d29ff..b0fae57 100644
--- a/src/register/prdfRegisterCache.C
+++ b/src/register/prdfRegisterCache.C
@@ -23,8 +23,9 @@
 /*                                                                        */
 /* IBM_PROLOG_END_TAG                                                     */
 
+#include <hei_includes.hpp>
+
 #include <prdfRegisterCache.H>
-#include <iipconst.h>
 
 namespace PRDF
 {