dt-bindings: auxdisplay: ht16k33: Use unevaluatedProperties to fix common property warning

Change additionalProperties to unevaluatedProperties because it refs to
/schemas/input/matrix-keymap.yaml.

Fix below CHECK_DTBS warnings:
arch/arm/boot/dts/nxp/imx/imx6dl-victgo.dtb: keypad@70 (holtek,ht16k33): 'keypad,num-columns', 'keypad,num-rows' do not match any of the regexes: '^pinctrl-[0-9]+$'
        from schema $id: http://devicetree.org/schemas/auxdisplay/holtek,ht16k33.yaml#

Fixes: f12b457c6b25c ("dt-bindings: auxdisplay: ht16k33: Convert to json-schema")
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>