arm64: dts: qcom: c630: Add backlight controller

The Lenovo Yoga C630 uses the PWM controller in the TI SN65DSI86 bridge
chip to provide a signal for the backlight control and has TLMM GPIO 11
attached to some regulator that drives the backlight.

Unfortunately the regulator attached to this gpio is also powering the
camera, so turning off backlight result in the detachment of the camera
as well.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: NSteev Klimaszewski <steev@kali.org>
Link: https://lore.kernel.org/r/20220208041606.144039-1-bjorn.andersson@linaro.org

arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts

@@ -59,6 +59,7 @@
 	panel {
 		compatible = "boe,nv133fhm-n61";
 		no-hpd;
+		backlight = <&backlight>;
 
 		ports {
 			port {
@@ -98,6 +99,12 @@
 
 		clock-frequency = <19200000>;
 	};
+
+	backlight: backlight {
+		compatible = "pwm-backlight";
+		pwms = <&sn65dsi86 1000000>;
+		enable-gpios = <&tlmm 11 GPIO_ACTIVE_HIGH>;
+	};
 };
 
 &adsp_pas {
@@ -419,6 +426,7 @@
 		clock-names = "refclk";
 
 		no-hpd;
+		#pwm-cells = <1>;
 
 		ports {
 			#address-cells = <1>;