Removes unused attribute accessors

Change-Id: If3628431d4ff5d153b284bc2d8e861094cf15f67
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/66878
Reviewed-by: Louis Stermole <stermole@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: PPE CI <ppe-ci+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: ANDRE A. MARIN <aamarin@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/66879
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

@@ -63,7 +63,6 @@
     2400 = 2400
   </enum>
   <platInit/>
-  <mssAccessorName>freq_mca_mhz</mssAccessorName>
 </attribute>
 <!-- ********************************************************************** -->
 <attribute>