dt-bindings: iio: vishay,vcnl4000: add interrupts property

The dtschema should list all properties, including the common ones like
interrupts.  This fixes dtbs_check warnings like:

  arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dt.yaml:
    prox@60: 'interrupt-parent', 'interrupts' do not match any of the regexes: 'pinctrl-[0-9]+'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200920203845.17758-1-krzk@kernel.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>