ACPI: Remove the ops field from struct acpi_device

The ops field in struct acpi_device is not used anywhere, so remove
it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

include/acpi/acpi_bus.h

@@ -271,7 +271,6 @@ struct acpi_device {
 	struct acpi_device_wakeup wakeup;
 	struct acpi_device_perf performance;
 	struct acpi_device_dir dir;
-	struct acpi_device_ops ops;
 	struct acpi_driver *driver;
 	void *driver_data;
 	struct device dev;