iio: light: add VEML6075 UVA and UVB light sensor driver

iio: light: add VEML6075 UVA and UVB light sensor driver

The Vishay VEMl6075 is a low power, 16-bit resolution UVA and UVB
light sensor with I2C interface and noise compensation (visible and
infrarred).

Every UV channel generates an output signal measured in counts per
integration period, where the integration time is configurable.

This driver adds support for both UV channels and the ultraviolet
index (UVI) inferred from them according to the device application note
with open-air (no teflon) coefficients.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20231110-veml6075-v3-3-6ee46775b422@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>