dt-bindings: leds: backlight: ktz8866: Add reg property and update example

The kinetic,ktz8866 is a I2C driver, so add the missing reg property.
And update example to make it clear.

Signed-off-by: Jianhua Lu <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Daniel Thompson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

Documentation/devicetree/bindings/leds/backlight/kinetic,ktz8866.yaml

···
   compatible:
     const: kinetic,ktz8866
 
+  reg:
+    maxItems: 1
+
   vddpos-supply:
     description: positive boost supply regulator.
 
···
 
 required:
   - compatible
+  - reg
   - vddpos-supply
   - vddneg-supply
   - enable-gpios
···
   - |
     #include <dt-bindings/gpio/gpio.h>
 
-    backlight {
-        compatible = "kinetic,ktz8866";
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
 
-        vddpos-supply = <&bl_vddpos_5p5>;
-        vddneg-supply = <&bl_vddneg_5p5>;
-        enable-gpios = <&tlmm 139 GPIO_ACTIVE_HIGH>;
-        current-num-sinks = <5>;
-        kinetic,current-ramp-delay-ms = <128>;
-        kinetic,led-enable-ramp-delay-ms = <1>;
-        kinetic,enable-lcd-bias;
+        backlight@11 {
+            compatible = "kinetic,ktz8866";
+            reg = <0x11>;
+            vddpos-supply = <&bl_vddpos_5p5>;
+            vddneg-supply = <&bl_vddneg_5p5>;
+            enable-gpios = <&tlmm 139 GPIO_ACTIVE_HIGH>;
+            current-num-sinks = <5>;
+            kinetic,current-ramp-delay-ms = <128>;
+            kinetic,led-enable-ramp-delay-ms = <1>;
+            kinetic,enable-lcd-bias;
+        };
     };