sched/cpufreq_sched: compute freq_new based on capacity_orig_of()

capacity is both cpu and freq scaled with EAS. We thus need to compute
freq_new using capacity_orig_of(), so that we properly scale back the thing
on heterogeneous architectures. In fact, capacity_orig_of() returns only
the cpu scaled part of capacity (see update_cpu_capacity()). So, to scale
freq_new correctly, we multiply policy->max by capacity/capacity_orig_of()
instead of capacity/1024.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

Signed-off-by: Juri Lelli <juri.lelli@arm.com>