cpufreq: Avoid calling cpufreq driver's target() routine if target_freq == policy->cur

Avoid calling cpufreq driver's target() routine if new frequency is same as
policies current frequency.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -1476,6 +1476,10 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 
 	pr_debug("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
 		target_freq, relation);
+
+	if (target_freq == policy->cur)
+		return 0;
+
 	if (cpu_online(policy->cpu) && cpufreq_driver->target)
 		retval = cpufreq_driver->target(policy, target_freq, relation);