ARM: 8497/1: initialize cpu_scale to its default

Instead of looping through all cpus calling set_capacity_scale, we can
initialise cpu_scale per-cpu variables to SCHED_CAPACITY_SCALE with their
definition.

Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>