cpufreq: dt: Register an Energy Model

Now that PM_OPP provides a helper function to estimate the power
consumed by CPUs, make sure to try and register an Energy Model (EM)
from cpufreq-dt, hence ensuring interested subsystems (the task
scheduler, for example) can make use of that information when available.

Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/cpufreq-dt.c

@@ -280,6 +280,8 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.transition_latency = transition_latency;
 	policy->dvfs_possible_from_any_cpu = true;
 
+	dev_pm_opp_of_register_em(policy->cpus);
+
 	return 0;
 
 out_free_cpufreq_table: