kernel: ACPI: acpi_pad: Fix memory leak in power saving threads

Fix once per second (round_robin_time) memory leak of about 1 KB in
each acpi_pad kernel idling thread that is activated.

Found by testing with kmemleak.

as per: 8b29d29abc

Thanks @edrikk for letting know

release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/acpi/acpi_pad.c

@@ -122,6 +122,7 @@ static void round_robin_cpu(unsigned int tsk_index)
 		cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
 	if (cpumask_empty(tmp)) {
 		mutex_unlock(&isolated_cpus_lock);
+		free_cpumask_var(tmp);
 		return;
 	}
 	for_each_cpu(cpu, tmp) {
@@ -139,6 +140,8 @@ static void round_robin_cpu(unsigned int tsk_index)
 	mutex_unlock(&isolated_cpus_lock);
 
 	set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
+
+	free_cpumask_var(tmp);
 }
 
 static void exit_round_robin(unsigned int tsk_index)