sony-laptop: 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: Mattia Dongili <malattia@linux.it>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/platform/x86/sony-laptop.c

@@ -69,6 +69,7 @@
 #include <linux/miscdevice.h>
 #endif
 #include <asm/uaccess.h>
+#include <acpi/video.h>
 
 #define dprintk(fmt, ...)			\
 do {						\
@@ -3198,12 +3199,8 @@ static int sony_nc_add(struct acpi_device *device)
 			sony_nc_function_setup(device, sony_pf_device);
 	}
 
-	/* setup input devices and helper fifo */
-	if (acpi_video_backlight_support()) {
-		pr_info("brightness ignored, must be controlled by ACPI video driver\n");
-	} else {
+	if (acpi_video_get_backlight_type() == acpi_backlight_vendor)
 		sony_nc_backlight_setup();
-	}
 
 	/* create sony_pf sysfs attributes related to the SNC device */
 	for (item = sony_nc_values; item->name; ++item) {