Enforce SMF size requirements and correct valid bit

- Minimum 256MB secure memory size required
- Only allow 256MB offsets to avoid mismatches in hw/attr values
- Only set SMF valid if there are ports in the group

Change-Id: Iffe0ded1a4c11523846fbf2778c5c317affc7d8f
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/67376
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: HWSV CI <hwsv-ci+hostboot@us.ibm.com>
Reviewed-by: Joseph J. McGill <jmcgill@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Thi N. Tran <thi@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/67435
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

@@ -1241,7 +1241,7 @@
   <id>ATTR_PROC_SMF_BAR_SIZE</id>
   <targetType>TARGET_TYPE_PROC_CHIP</targetType>
   <description> The total amount of memory a user has requested to reserve for
-                secure memory functions.
+                secure memory functions. Minimum requirement of 256MB.
                 Used by p9_mss_eff_grouping.
   </description>
   <valueType>uint64</valueType>
@@ -1257,10 +1257,6 @@
       1_GB = 0x0000000040000000,
     512_MB = 0x0000000020000000,
     256_MB = 0x0000000010000000,
-    128_MB = 0x0000000008000000,
-     64_MB = 0x0000000004000000,
-     32_MB = 0x0000000002000000,
-     16_MB = 0x0000000001000000,
       ZERO = 0x0000000000000000
   </enum>
   <initToZero/>