hwmon: add POWER-Z driver

hwmon: add POWER-Z driver

POWER-Z is a series of devices to monitor power characteristics of
USB-C connections and display those on a on-device display.
Some of the devices, notably KM002C and KM003C, contain an additional
port which exposes the measurements via USB.

This is a driver for this monitor port.

It was developed and tested with the KM003C.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20230902-powerz-v4-1-7ec2c1440687@weissschuh.net
[groeck:
 Release urb after hwmon registration error;
 Move priv->status initialization to correct place before reinit_completion
 ]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>