PM / QoS: correct the valid range of pm_qos_class

The valid start index for pm_qos_array is not 0, but
PM_QOS_CPU_DMA_LATENCY. There is a null_pm_qos at index 0 of
pm_qos_array. However, null_pm_qos is not created as misc device so
that inclusion of 0 index for checking pm_qos_class especially for
file operations is not proper here.

[rjw: Changelog, a bit]
Signed-off-by: Sahara <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

kernel/power/qos.c

···
 {
 	int pm_qos_class;
 
-	for (pm_qos_class = 0;
+	for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
 		pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 		if (minor ==
 			pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
···
 	long pm_qos_class;
 
 	pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
-	if (pm_qos_class >= 0) {
+	if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
 		struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
 		if (!req)
 			return -ENOMEM;
···
 
 	BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
 
-	for (i = 1; i < PM_QOS_NUM_CLASSES; i++) {
+	for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
 		ret = register_pm_qos_misc(pm_qos_array[i]);
 		if (ret < 0) {
 			printk(KERN_ERR "pm_qos_param: %s setup failed\n",