Disable RTT_WR during WR_LEVEL cal step, and set equivalent terminations

Change-Id: Ie813c26588d803371e35790ab9b233630c5041b4
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/37203
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Brian R. Silver <bsilver@us.ibm.com>
Reviewed-by: JACOB L. HARVEY <jlharvey@us.ibm.com>
Dev-Ready: Louis Stermole <stermole@us.ibm.com>
Reviewed-by: Matt K. Light <mklight@us.ibm.com>
Reviewed-by: Christian R. Geddes <crgeddes@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/69800
Reviewed-by: Sachin Gupta <sgupta2m@in.ibm.com>
Tested-by: Sachin Gupta <sgupta2m@in.ibm.com>

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

@@ -3144,4 +3144,20 @@
         <mssAccessorName>eff_rank_group_override</mssAccessorName>
     </attribute>
 
+    <attribute>
+        <id>ATTR_MSS_RTT_NOM_OVERRIDE_DISABLE</id>
+        <targetType>TARGET_TYPE_MCS</targetType>
+        <description>
+          Set equal to 1 to disable setting of RTT_NOM to use RTT_WR values
+          during WR_LEVEL calibration.
+        </description>
+        <initToZero></initToZero>
+        <valueType>uint8</valueType>
+        <writeable/>
+        <enum>NO = 0, YES = 1</enum>
+        <mssUnits> bool </mssUnits>
+        <array> 2 2 </array>
+        <mssAccessorName>rtt_nom_override_disable</mssAccessorName>
+    </attribute>
+
 </attributes>