Set PROC_SBE_IS_MASTER on master proc when we read mbox regs

When initializing the targeting service we set up some attributes.
One attribute that we are not setting that would be useful later
is this PROC_SBE_IS_MASTER attribute. We know at this time which
proc is master so we will set the attribute on the master proc

Change-Id: Ib927a0b7dc2e6ef10d82ca699323e07516750ee9
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/39003
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Reviewed-by: Dean Sanner <dsanner@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: Christian R. Geddes <crgeddes@us.ibm.com>

src/usr/targeting/targetservicestart.C

@@ -300,6 +300,7 @@ static void initializeAttributes(TargetService& i_targetService,
             l_i2c_switches.useFsiI2C  = 0;
             l_pMasterProcChip->setAttr<ATTR_I2C_SWITCHES>(l_i2c_switches);
 
+            l_pMasterProcChip->setAttr<ATTR_PROC_SBE_MASTER_CHIP>(1);
 
             // Master has SBE started
             l_pMasterProcChip->setAttr<ATTR_SBE_IS_STARTED>(1);