ACPI: introduce helper function acpi_execute_simple_method()

Introduce helper function acpi_execute_simple_method() and use it in
a number of places to simplify code.

[rjw: Changelog]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index 5c28c89..1460c88 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -637,9 +637,7 @@
 	}
 
 	/* Execute _PSW */
-	arg_list.count = 1;
-	in_arg[0].integer.value = enable;
-	status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
+	status = acpi_execute_simple_method(dev->handle, "_PSW", enable);
 	if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 		printk(KERN_ERR PREFIX "_PSW execution failed\n");
 		dev->wakeup.flags.valid = 0;