iio: adc: adding support for PAC193x

This is the iio driver for Microchip
PAC193X series of Power Monitor with Accumulator chip family.

Signed-off-by: Marius Cristea <marius.cristea@microchip.com>
Link: https://lore.kernel.org/r/20240222164206.65700-3-marius.cristea@microchip.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>