fix bug in PR code to handle proc with 0 EX units.
fix bug in PR code to handle proc with 0 EX units.

Change-Id: If9115324a79f21fe4fdb3c3f9271d48146e77dda
RTC: 72363
Tested-by: Jenkins Server
Reviewed-by: Andrew J. Geissler <c46de238cd554860f0bd4010b1729f1323facd9c@us.ibm.com>
Reviewed-by: A. Patrick Williams III <c87e37b1a4035affd737b461af89fb722d635f4d@us.ibm.com>

open-power/hostboot,csmart/hostboot,open-power/hostboot,Over-enthusiastic/hostboot,alvintpwang/hostboot,csmart/hostboot,csmart/hostboot,Over-enthusiastic/hostboot,alvintpwang/hostboot,Over-enthusiastic/hostboot,csmart/hostboot,alvintpwang/hostboot,csmart/hostboot,open-power/hostboot,alvintpwang/hostboot,alvintpwang/hostboot,Over-enthusiastic/hostboot,Over-enthusiastic/hostboot,open-power/hostboot,open-power/hostboot