sched/topology: Mark SD_BALANCE_WAKE as SDF_NEEDS_GROUPS

Even if no mainline topology uses this flag, it is a load balancing flag
just like SD_BALANCE_FORK and requires 2+ groups to have any effect.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-13-valentin.schneider@arm.com

include/linux/sched/sd_flags.h

@@ -70,8 +70,9 @@ SD_FLAG(SD_BALANCE_FORK, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
  * Balance on wakeup
  *
  * SHARED_CHILD: Set from the base domain up to cpuset.sched_relax_domain_level.
+ * NEEDS_GROUPS: Load balancing flag.
  */
-SD_FLAG(SD_BALANCE_WAKE, SDF_SHARED_CHILD)
+SD_FLAG(SD_BALANCE_WAKE, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
 
 /*
  * Consider waking task on waking CPU.