libata-acpi.c: fix copy and paste mistake in ata_acpi_register_power_resource

Fix a copy and paste mistake introduced in:

commit bc9b6407
"ACPI / PM: Rework the handling of devices depending on power resources"
Signed-off-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-acpi.c

@@ -1027,7 +1027,7 @@ static void ata_acpi_register_power_resource(struct ata_device *dev)
 
 	handle = ata_dev_acpi_handle(dev);
 	if (handle)
-		acpi_dev_pm_remove_dependent(handle, &sdev->sdev_gendev);
+		acpi_dev_pm_add_dependent(handle, &sdev->sdev_gendev);
 }
 
 static void ata_acpi_unregister_power_resource(struct ata_device *dev)