sched/tracing: Fix format specifiers in sched_compute_energy

The energy values passed to sched_compute_energy trace event
are of unsigned long type. So use %lu format specifier instead
of %llu.

Change-Id: I1e82b34559d76d5cfb023598a8ce62917281a9af
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>