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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/devicetree/bindings/iio/light/vishay,vcnl4000.yaml

···
       - vishay,vcnl4020
       - vishay,vcnl4040
       - vishay,vcnl4200
+
+  interrupts:
+    maxItems: 1
+
   reg:
     maxItems: 1