dt-bindings: iio: light: vcnl4000: add regulators

dt-bindings: iio: light: vcnl4000: add regulators

These sensors can accept 2 supplies - one for the sensor and one for IR
LED [1]. Add supply properties for the sensor - 2 for the sensors and
one external, for their open drain interrupt line, to ensure the sensor
is powered on before proceeding with setup.

[1] https://www.vishay.com/docs/84274/vcnl4040.pdf

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Erikas Bitovtas <xerikasxx@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>