p9_cen_ref_clk_enable -- p9 initial version

1) attr ATTR_DMI_REFCLOCK_SWIZZLE for mapping
2) root control 6 manipulated for clk enabling

Change-Id: I4d18d1a8003951705d316e504b9d3445c96224be
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/39347
Reviewed-by: Thi N. Tran <thi@us.ibm.com>
Reviewed-by: Joseph J. McGill <jmcgill@us.ibm.com>
Reviewed-by: Matt K. Light <mklight@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: PPE CI <ppe-ci+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/39388
Reviewed-by: Hostboot Team <hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Sachin Gupta <sgupta2m@in.ibm.com>

src/import/chips/p9/procedures/xml/attribute_info/nest_attributes.xml

@@ -718,9 +718,12 @@
 <!-- ********************************************************************** -->
 <attribute>
   <id>ATTR_DMI_REFCLOCK_SWIZZLE</id>
-  <targetType>TARGET_TYPE_MCS</targetType>
-  <description>Define DMI Ref clock/Swizzle for Centaur.
-   Provided by the MRW</description>
+  <targetType>TARGET_TYPE_DMI</targetType>
+  <description>
+      Define DMI Ref clock/Swizzle for Centaur.
+      Mapper from DMI unit id -> ROOT CNTL 6 refclk drive enable bit
+      consumer: p9_cen_ref_clk_enable
+      </description>
   <valueType>uint8</valueType>
   <persistRuntime/>
   <platInit/>