Change kernel string to hostboot.
Change kernel string to hostboot.

Change-Id: I6da5c1686ce60af9a6610c21cad3765c8a8219d9
Reviewed-on: http://localhost:8080/gerrit/3
Tested-by: Jenkins Server
Reviewed-by: ALWOOD P. WILLIAMS III <c87e37b1a4035affd737b461af89fb722d635f4d@us.ibm.com>

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