arm64: dts: renesas: r8a77995: draak: Set better backlight levels

The backlight levels provided in the Draak DT produce a perceived
brightness very biased towards high brightness. Use better brightness
levels based on the CIE 1931 formula.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a77995-draak.dts

@@ -28,8 +28,8 @@ backlight: backlight {
 		compatible = "pwm-backlight";
 		pwms = <&pwm1 0 50000>;
 
-		brightness-levels = <256 128 64 16 8 4 0>;
-		default-brightness-level = <6>;
+		brightness-levels = <512 511 505 494 473 440 392 327 241 133 0>;
+		default-brightness-level = <10>;
 
 		power-supply = <&reg_12p0v>;
 		enable-gpios = <&gpio4 0 GPIO_ACTIVE_HIGH>;