From: Nick Piggin <piggin@cyberone.com.au>

The following patch implements a cpu_power member to struct sched_group.

This allows special casing to be removed for SMT groups in the balancing
code.  It does not take CPU hotplug into account yet, but that shouldn't be
too hard.

I have tested it on the NUMAQ by pretending it has SMT.  Works as expected.
Active balances across nodes.