Secure Boot; Force simultaneous SBE update on key transition

- Forces simultaneous SBE update in sequential mode during key transition

Change-Id: If660c99a43dcbb465ca962ca060f52e63f9cd97c
RTC: 180784
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/50610
Reviewed-by: Martin Gloff <mgloff@us.ibm.com>
Reviewed-by: Stephen M. Cprek <smcprek@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
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: Michael Baiocchi <mbaiocch@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>