driver core: make /sys/power a kobject

/sys/power should not be a kset, that's overkill.  This patch renames it
to power_kset and fixes up all usages of it in the tree.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

kernel/power/disk.c

@@ -714,7 +714,7 @@ static struct attribute_group attr_group = {
 
 static int __init pm_disk_init(void)
 {
-	return sysfs_create_group(&power_kset->kobj, &attr_group);
+	return sysfs_create_group(power_kobj, &attr_group);
 }
 
 core_initcall(pm_disk_init);