dell-laptop: Port to new backlight interface selection API

Port the backlight selection logic to the new backlight interface
selection API.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/platform/x86/dell-laptop.c

@@ -31,6 +31,7 @@
 #include <linux/slab.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <acpi/video.h>
 #include "../../firmware/dcdbas.h"
 
 #define BRIGHTNESS_TOKEN 0x7d
@@ -1920,13 +1921,8 @@ static int __init dell_init(void)
 		debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
 				    &dell_debugfs_fops);
 
-#ifdef CONFIG_ACPI
-	/* In the event of an ACPI backlight being available, don't
-	 * register the platform controller.
-	 */
-	if (acpi_video_backlight_support())
+	if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
 		return 0;
-#endif
 
 	get_buffer();
 	buffer->input[0] = find_token_location(BRIGHTNESS_TOKEN);