iio: adc: add support for Nuvoton NCT7201

iio: adc: add support for Nuvoton NCT7201

Add Nuvoton NCT7201/NCT7202 system voltage monitor 12-bit ADC driver

NCT7201/NCT7202 supports up to 12 analog voltage monitor inputs and up
to 4 SMBus addresses by ADDR pin. Meanwhile, ALERT# hardware event pins
for independent alarm signals, and all the threshold values could be set
for system protection without any timing delay. It also supports reset
input RSTIN# to recover system from a fault condition.

Currently, only single-edge mode conversion and threshold events are
supported.

Signed-off-by: Eason Yang <j2anfernee@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20250512083156.3300006-3-j2anfernee@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>