[CPUFREQ] fix cpumask memory leak in acpi-cpufreq on cpu hotplug.

I came across a memory leak during a cyclic cpu-online-offline test.
Signed-off-by: Yu Luming <luming.yu@intel.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Jones <davej@redhat.com>

drivers/cpufreq/acpi-cpufreq.c

@@ -759,7 +759,7 @@ static void __exit acpi_cpufreq_exit(void)
 
 	cpufreq_unregister_driver(&acpi_cpufreq_driver);
 
-	free_percpu(acpi_perf_data);
+	free_acpi_perf_data();
 }
 
 module_param(acpi_pstate_strict, uint, 0644);