sched: Fix compile error for UP,!NOHZ

Commit 69e1e811 ("sched, nohz: Track nr_busy_cpus in the
sched_group_power") messed up the static inline function definition.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/n/tip-abjah8ctq5qrjjtdiabe8lph@git.kernel.org


Signed-off-by: Ingo Molnar <mingo@elte.hu>