arm64: dts: mediatek: mt6795-xperia-m5: Add display backlight support

Add the relevant nodes for display backlight on Sony Xperia M5: this
needs both the SoC PWM IP and MT6332 PMIC LED strings.

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230721082822.680010-3-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Author: AngeloGioacchino Del Regno

arch/arm64/boot/dts/mediatek/mt6795-sony-xperia-m5.dts

@@ -22,6 +22,23 @@
 		serial1 = &uart1;
 	};
 
+	backlight_lcd0: backlight {
+		compatible = "led-backlight";
+		leds = <&disp_led_pwm>, <&pmic_bl_led>;
+
+		default-brightness-level = <300>;
+	};
+
+	led-controller-display {
+		compatible = "pwm-leds";
+
+		disp_led_pwm: led-0 {
+			label = "backlight-pwm";
+			pwms = <&pwm0 0 500000>;
+			max-brightness = <1024>;
+		};
+	};
+
 	memory@40000000 {
 		device_type = "memory";
 		reg = <0 0x40000000 0 0x1e800000>;
@@ -338,6 +355,21 @@
 	 * an interrupt on the companion, so we use the MT6332 IRQ GPIO.
 	 */
 	interrupts = <GIC_SPI 160 IRQ_TYPE_LEVEL_HIGH>;
+
+	mt6332-led {
+		compatible = "mediatek,mt6332-led";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		pmic_bl_led: led@0 {
+			reg = <0>;
+			label = "backlight-pmic";
+		};
+	};
+};
+
+&pwm0 {
+	status = "okay";
 };
 
 &uart0 {