cpufreq: Fix clamp_val() usage in cpufreq_driver_fast_switch()

The return value of clamp_val() has to be stored actually.

Fixes: b7898fda5bc7 (cpufreq: Support for fast frequency switching)
Reported-by: Steve Muckle <steve.muckle@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/cpufreq.c

@@ -1832,7 +1832,7 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier);
 unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
 					unsigned int target_freq)
 {
-	clamp_val(target_freq, policy->min, policy->max);
+	target_freq = clamp_val(target_freq, policy->min, policy->max);
 
 	return cpufreq_driver->fast_switch(policy, target_freq);
 }