iio: adc: pac1921: Add ACPI support to Microchip pac1921

iio: adc: pac1921: Add ACPI support to Microchip pac1921

This patch implements ACPI support to Microchip pac1921.
The driver can read the shunt resistor value and label from the ACPI table.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Matteo Martelli <matteomartelli3@gmail.com>
Signed-off-by: Victor Duicu <victor.duicu@microchip.com>
Link: https://patch.msgid.link/20241115133436.13204-1-victor.duicu@microchip.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>