iio: add modifiers for A and B ultraviolet light

iio: add modifiers for A and B ultraviolet light

Currently there are only two modifiers for ultraviolet light: a generic
one for any ultraviolet light (IIO_MOD_LIGHT_UV) and one for deep
ultraviolet (IIO_MOD_LIGHT_DUV), which is also referred as ultraviolet
C (UV-C) band and covers short-wave ultraviolet.

There are still no modifiers for the long-wave and medium-wave
ultraviolet bands. These two bands are the main components used to
obtain the UV index on the Earth's surface.

Add modifiers for the ultraviolet A (UV-A) and ultraviolet B (UV-B)
bands.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20231110-veml6075-v3-1-6ee46775b422@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>