ACPI / memhotplug: Use defined marco METHOD_NAME__STA

We already have predefined marco for method name "_STA', so
using the marco instead of directly using the string.
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_memhotplug.c

@@ -152,8 +152,9 @@ static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
 	unsigned long long current_status;
 
 	/* Get device present/absent information from the _STA */
-	if (ACPI_FAILURE(acpi_evaluate_integer(mem_device->device->handle, "_STA",
-					       NULL, &current_status)))
+	if (ACPI_FAILURE(acpi_evaluate_integer(mem_device->device->handle,
+					       METHOD_NAME__STA, NULL,
+					       &current_status)))
 		return -ENODEV;
 	/*
 	 * Check for device status. Device should be