Save current task in interrupt path.
Save current task in interrupt path.

Change-Id: I4cdcf3b4f93bd75aca4a495f3faa16af9ba217d7
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/753
Tested-by: Jenkins Server
Reviewed-by: Douglas R. Gilbert <54dff2264884c355ed5584a3b7f1530b4b26921e@us.ibm.com>
Reviewed-by: A. Patrick Williams III <c87e37b1a4035affd737b461af89fb722d635f4d@us.ibm.com>

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