ACPI / Battery: Add the check before refresh sysfs in the battery_notify()

In the commit 25be5821, add the refresh sysfs when system resumes
from suspending. But it didn't check that the battery exists. This
will cause battery sysfs files added when the battery doesn't exist.
This patch add the check before refreshing.

	https://bugzilla.kernel.org/show_bug.cgi?id=35642Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/battery.c

@@ -949,8 +949,10 @@ static int battery_notify(struct notifier_block *nb,
 	switch (mode) {
 	case PM_POST_HIBERNATION:
 	case PM_POST_SUSPEND:
+		if (battery->bat.dev) {
 			sysfs_remove_battery(battery);
 			sysfs_add_battery(battery);
+		}
 		break;
 	}