arm64: dts: allwinner: add backlight regulator for Pinebook

Backlight power is controlled by PH6 GPIO, so add corresponding
regulator-fixed node for it. Otherwise backlight won't light up
if bootloader doesn't enable it.
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm64/boot/dts/allwinner/sun50i-a64-pinebook.dts

@@ -22,12 +22,22 @@ aliases {
 		ethernet0 = &rtl8723cs;
 	};
 
+	vdd_bl: regulator@0 {
+		compatible = "regulator-fixed";
+		regulator-name = "bl-3v3";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		gpio = <&pio 7 6 GPIO_ACTIVE_HIGH>; /* PH6 */
+		enable-active-high;
+	};
+
 	backlight: backlight {
 		compatible = "pwm-backlight";
 		pwms = <&pwm 0 50000 0>;
 		brightness-levels = <0 5 10 15 20 30 40 55 70 85 100>;
 		default-brightness-level = <2>;
 		enable-gpios = <&pio 3 23 GPIO_ACTIVE_HIGH>; /* PD23 */
+		power-supply = <&vdd_bl>;
 	};
 
 	chosen {