ACPI: introduce helper function acpi_has_method()

Introduce helper function acpi_has_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/battery.c b/drivers/acpi/battery.c
index 082b4dd..a762716 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -548,12 +548,8 @@
 
 static int acpi_battery_init_alarm(struct acpi_battery *battery)
 {
-	acpi_status status = AE_OK;
-	acpi_handle handle = NULL;
-
 	/* See if alarms are supported, and if so, set default */
-	status = acpi_get_handle(battery->device->handle, "_BTP", &handle);
-	if (ACPI_FAILURE(status)) {
+	if (!acpi_has_method(battery->device->handle, "_BTP")) {
 		clear_bit(ACPI_BATTERY_ALARM_PRESENT, &battery->flags);
 		return 0;
 	}
@@ -1066,7 +1062,7 @@
 {
 	int result = 0;
 	struct acpi_battery *battery = NULL;
-	acpi_handle handle;
+
 	if (!device)
 		return -EINVAL;
 	battery = kzalloc(sizeof(struct acpi_battery), GFP_KERNEL);
@@ -1078,8 +1074,7 @@
 	device->driver_data = battery;
 	mutex_init(&battery->lock);
 	mutex_init(&battery->sysfs_lock);
-	if (ACPI_SUCCESS(acpi_get_handle(battery->device->handle,
-			"_BIX", &handle)))
+	if (acpi_has_method(battery->device->handle, "_BIX"))
 		set_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags);
 	result = acpi_battery_update(battery);
 	if (result)