dt-bindings: mtd: mxc-nand: Drop undocumented properties from example

With unevaluatedProperties issues fixed, 'nand-bus-width' and
'nand-ecc-mode' are flagged as undocumented. Removing them from the example
is the easiest solution to silence the warnings.
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220525205947.2487165-1-robh@kernel.org

Documentation/devicetree/bindings/mtd/mxc-nand.yaml

@@ -37,6 +37,4 @@ examples:
         compatible = "fsl,imx27-nand";
         reg = <0xd8000000 0x1000>;
         interrupts = <29>;
-        nand-bus-width = <8>;
-        nand-ecc-mode = "hw";
     };