acpi_pad: squish warning

drivers/acpi/acpi_pad.c: In function 'power_saving_thread':
drivers/acpi/acpi_pad.c:103: warning: 'preferred_cpu' may be used uninitialized in this function

Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/acpi_pad.c

@@ -100,7 +100,8 @@ static void round_robin_cpu(unsigned int tsk_index)
 	struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
 	cpumask_var_t tmp;
 	int cpu;
-	unsigned long min_weight = -1, preferred_cpu;
+	unsigned long min_weight = -1;
+	unsigned long uninitialized_var(preferred_cpu);
 
 	if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 		return;