dt-bindings: display: clps711x-fb: fix native-mode setting

Move the native-mode setting inside the display-timing node. Outside of
display-timing, it is ignored.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/display/cirrus,clps711x-fb.txt

@@ -27,11 +27,11 @@ Example:
 
 	display: display {
 		model = "320x240x4";
-		native-mode = <&timing0>;
 		bits-per-pixel = <4>;
 		ac-prescale = <17>;
 
 		display-timings {
+			native-mode = <&timing0>;
 			timing0: 320x240 {
 				hactive = <320>;
 				hback-porch = <0>;