dt-bindings: display: imx: 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/imx/fsl,imx-fb.txt

@@ -38,10 +38,10 @@ Example:
 
 	display0: display0 {
 		model = "Primeview-PD050VL1";
-		native-mode = <&timing_disp0>;
 		bits-per-pixel = <16>;
 		fsl,pcr = <0xf0c88080>;	/* non-standard but required */
 		display-timings {
+			native-mode = <&timing_disp0>;
 			timing_disp0: 640x480 {
 				hactive = <640>;
 				vactive = <480>;