hwmon: add driver for NZXT RGB&Fan Controller/Smart Device v2.

This driver implements monitoring and control of fans plugged into the
device. Besides typical speed monitoring and PWM duty cycle control,
voltage and current are reported for every fan.

The device also has 2 connectors for RGB LEDs, support for them isn't
implemented (mainly because there is no standardized sysfs interface).

Also, the device has a noise sensor, but the sensor seems to be completely
useless (and very imprecise), so support for it isn't implemented too.

The driver coexists with userspace tools that access the device through
hidraw interface with no known issues.

The driver has been tested on x86_64, built in and as a module.

Some changes/improvements were suggested by Jonas Malaco.

Signed-off-by: Aleksandr Mezin <mezin.alexander@gmail.com>
Link: https://lore.kernel.org/r/20211031033058.151014-1-mezin.alexander@gmail.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>