sched/fair: fix energy compute when a cluster is only a cpu core in multi-cluster system

when a cluster is only a cpu core in multi-cluster system, compute_energy will only
compute cpu core power(MC domain),but the power consumed by the DIE domain is not
computed.

fix the bug,end compute energy in DIE domain.

Bug: 120440300
Signed-off-by: Samer Xie <samer.xie@unisoc.com>