iio: light: vcnl4000: add support for regulators

iio: light: vcnl4000: add support for regulators

Add supply, I2C and cathode voltage regulators to the sensor and enable
them. This keeps the sensor powered on even after its only supply shared
by another device shuts down.

Reported-by: Raymond Hackley <raymondhackley@protonmail.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Erikas Bitovtas <xerikasxx@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>