Fix persistency of ATTR_KEY_CLEAR_REQUEST

This commit changes the persistency of ATTR_KEY_CLEAR_REQUEST
from volatile-zeroed to non-volatile.

Change-Id: Iea2dc1bdc25a862632655cc141db554a93caf3bd
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/96791
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Reviewed-by: Christopher J Engel <cjengel@us.ibm.com>
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP HW <op-hw-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Nicholas E Bofferding <bofferdn@us.ibm.com>

src/usr/targeting/common/xmltohb/attribute_types.xml

@@ -2975,7 +2975,7 @@
     <description>
         Indicates types of Key Clear Requests are being made
     </description>
-    <persistency>volatile-zeroed</persistency>
+    <persistency>non-volatile</persistency>
     <readable/>
     <simpleType>
       <enumeration>