Don't customize risk level into SBE image, default to risk 0

Change-Id: I23eac7dfa803d9de8e51af478d4e99fa301ea5b4
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/37165
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Claus M. Olsen <cmolsen@us.ibm.com>
Reviewed-by: Joseph J. McGill <jmcgill@us.ibm.com>
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/37170
Reviewed-by: Hostboot Team <hostboot@us.ibm.com>
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-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

@@ -93,7 +93,7 @@ fapi2::ReturnCode writeMboxRegs (
     MBOX_ATTR_WRITE (ATTR_NEST_MEM_X_O_PCI_BYPASS,  i_proc_target,   i_image);
     MBOX_ATTR_WRITE (ATTR_SYSTEM_IPL_PHASE,         FAPI_SYSTEM,     i_image);
     MBOX_ATTR_WRITE (ATTR_SYS_FORCE_ALL_CORES,      FAPI_SYSTEM,     i_image);
-    MBOX_ATTR_WRITE (ATTR_RISK_LEVEL,               FAPI_SYSTEM,     i_image);
+    MBOX_ATTR_CLEAR (ATTR_RISK_LEVEL,               FAPI_SYSTEM,     i_image);
     MBOX_ATTR_WRITE (ATTR_DISABLE_HBBL_VECTORS,     FAPI_SYSTEM,     i_image);
     MBOX_ATTR_WRITE (ATTR_MC_SYNC_MODE,             i_proc_target,   i_image);
     MBOX_ATTR_WRITE (ATTR_SECURITY_MODE,            FAPI_SYSTEM,     i_image);