Set SMF_CONFIG Attribute in MBOX Scratch Reg

ATTR_SMF_CONFIG was not being written into the scratch reg 6
correctly, which was one of the causes of issues with SMF
on OpenPOWER systems. This commit enables that attribute to
be written to the scratch reg.

Change-Id: I2b8a8c789ed520f6e10ca6d5626f536ee6164afc
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/81949
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Tested-by: HWSV CI <hwsv-ci+hostboot@us.ibm.com>
Reviewed-by: Michael Baiocchi <mbaiocch@us.ibm.com>
Reviewed-by: Claus M Olsen <cmolsen@us.ibm.com>
Reviewed-by: Jennifer A Stofer <stofer@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/81979
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP HW <op-hw-jenkins+hostboot@us.ibm.com>
Reviewed-by: Daniel M Crowell <dcrowell@us.ibm.com>

src/import/chips/p9/procedures/hwp/customize/p9_xip_customize.C

@@ -305,6 +305,7 @@ fapi2::ReturnCode writeMboxRegs (
     MBOX_ATTR_WRITE (ATTR_PROC_EPS_WRITE_CYCLES_T2, FAPI_SYSTEM,    i_image);
     MBOX_ATTR_WRITE (ATTR_LPC_CONSOLE_CNFG,         i_procTarget,   i_image);
     MBOX_ATTR_WRITE (ATTR_SBE_NVDIMM_IN_PORT,       i_procTarget,   i_image);
+    MBOX_ATTR_WRITE (ATTR_SMF_CONFIG,               FAPI_SYSTEM,    i_image);
 
     // for backwards compatiblity with images that don't contain
     // the OB/MC PLL bucket attributes, ensure that the item exists