When the capacity drops low, we want to migrate load away. Allow the
load-balancer to remove all tasks when we hit rock bottom.

[ dino: backport to 31-rt ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: John Kacur <jkacur@redhat.com>
[ego@in.ibm.com: fix to update_sd_power_savings_stats]
Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>