Updates WR VREF for characterization results

Change-Id: I9803ee77afa2ebc32e12d9d528ac4ae6a6c947f8
CQ:SW411492
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/50709
Dev-Ready: STEPHEN GLANCY <sglancy@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Louis Stermole <stermole@us.ibm.com>
Reviewed-by: ANDRE A. MARIN <aamarin@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: HWSV CI <hwsv-ci+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/69809
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

@@ -3281,4 +3281,17 @@
         <mssAccessorName>phy_seq_refresh</mssAccessorName>
     </attribute>
 
+    <attribute>
+      <id>ATTR_MSS_WR_VREF_OFFSET</id>
+      <targetType>TARGET_TYPE_MCBIST</targetType>
+      <description>
+        Offsets the WR VREF value from the VPD when creating the eff config WR VREF attributes.
+      </description>
+      <default>0</default>
+      <valueType>int8</valueType>
+      <writeable/>
+      <platInit/>
+      <mssAccessorName>wr_vref_offset</mssAccessorName>
+    </attribute>
+
 </attributes>