Modified gen_accessors script for greater support

Added support for PROC TARGET, only creates accessors for
attributes that have the mssAccessorName xml tag, added support
for other non-mss attrs that don't have [port][dimm] indexes
and that have target types other than MCS, MCBIST, and SYSTEM

Change-Id: I44428bdef703dc7c95bbbe217921764a3b27d3da
Original-Change-Id: I6c76f8e7bbc0be1dade3f77f78d3371d16b609b2
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/44255
Reviewed-by: Louis Stermole <stermole@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: JACOB L. HARVEY <jlharvey@us.ibm.com>
Reviewed-by: Matt K. Light <mklight@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/gerrit1/55835
Reviewed-by: Sachin Gupta <sgupta2m@in.ibm.com>
Tested-by: Sachin Gupta <sgupta2m@in.ibm.com>

src/import/hwpf/fapi2/xml/attribute_info/system_attributes.xml

@@ -30,6 +30,7 @@
     <description>env: 1 = Awan/HWSimulator. 0 = Simics/RealHW.</description>
     <valueType>uint8</valueType>
     <platInit/>
+    <mssAccessorName>is_simulation</mssAccessorName>
   </attribute>
   <!-- ********************************************************************* -->
   <attribute>
@@ -77,6 +78,7 @@
 -->
     </enum>
     <platInit/>
+    <mssAccessorName>mnfg_flags</mssAccessorName>
   </attribute>
   <attribute>
     <id>ATTR_RECONFIGURE_LOOP</id>