energy_model: everything but kthread and dvfs
kthread
energy_model: remove dead code
fair.c: rename arch_eval_cpu_freq and add arch_scale_cpu_freq
fair.c: rename arch_scale_cpu_freq
fair.c: rename arch_scale_cpu_freq callsites
fair.c: protect arch_scale_cpu_freq with energy_aware
energy_model: it doesn't crash
energy_model: challenge complete