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/bus.c b/drivers/acpi/bus.c
index a5bb33b..a5a032e 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -593,8 +593,6 @@
 static int __init acpi_bus_init_irq(void)
 {
 	acpi_status status;
-	union acpi_object arg = { ACPI_TYPE_INTEGER };
-	struct acpi_object_list arg_list = { 1, &arg };
 	char *message = NULL;
 
 
@@ -623,9 +621,7 @@
 
 	printk(KERN_INFO PREFIX "Using %s for interrupt routing\n", message);
 
-	arg.integer.value = acpi_irq_model;
-
-	status = acpi_evaluate_object(NULL, "\\_PIC", &arg_list, NULL);
+	status = acpi_execute_simple_method(NULL, "\\_PIC", acpi_irq_model);
 	if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
 		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PIC"));
 		return -ENODEV;