iio: light: Add support for vishay vcnl4035

Add support for VCNL4035, which is capable of Ambient light
sensing (ALS) and proximity function. This patch adds support
only for ALS function

Signed-off-by: Parthiban Nallathambi <pn@denx.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>