asus-wmi: Port to new backlight interface selection API

Port the backlight selection logic to the new backlight interface
selection API.

This commit also removes various obsolete pr_xxx messages related to
backlight interface selection. These are obsolete because they assume
there is only a vendor or acpi backlight driver and no other choice.
Also they are not necessary, if the user wants to know which backlight
interfaces are registered a simple "ls /sys/class/backlight" suffices.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/platform/x86/asus-wmi.c

@@ -1364,7 +1364,7 @@ static void asus_wmi_notify(u32 value, void *context)
 		code = ASUS_WMI_BRN_DOWN;
 
 	if (code == ASUS_WMI_BRN_DOWN || code == ASUS_WMI_BRN_UP) {
-		if (!acpi_video_backlight_support()) {
+		if (acpi_video_get_backlight_type() == acpi_backlight_vendor) {
 			asus_wmi_backlight_notify(asus, orig_code);
 			goto exit;
 		}
@@ -1772,17 +1772,16 @@ static int asus_wmi_add(struct platform_device *pdev)
 	   stop this from showing up */
 	chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
 	if (chassis_type && !strcmp(chassis_type, "3"))
-		acpi_video_dmi_promote_vendor();
+		acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);
+
 	if (asus->driver->quirks->wmi_backlight_power)
-		acpi_video_dmi_promote_vendor();
-	if (!acpi_video_backlight_support()) {
-		pr_info("Disabling ACPI video driver\n");
-		acpi_video_unregister_backlight();
+		acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);
+
+	if (acpi_video_get_backlight_type() == acpi_backlight_vendor) {
 		err = asus_wmi_backlight_init(asus);
 		if (err && err != -ENODEV)
 			goto fail_backlight;
-	} else
-		pr_info("Backlight controlled by ACPI video driver\n");
+	}
 
 	status = wmi_install_notify_handler(asus->driver->event_guid,
 					    asus_wmi_notify, asus);