hwmon: (k10temp) Remove support for displaying voltage and current on Zen CPUs

Voltages and current are reported by Zen CPUs. However, the means
to do so is undocumented, changes from CPU to CPU, and the raw data
is not calibrated. Calibration information is available, but again
not documented. This results in less than perfect user experience,
up to concerns that loading the driver might possibly damage
the hardware (by reporting out-of range voltages). Effectively
support for reporting voltages and current is not maintainable.
Drop it.

Cc: Artem S. Tashkinov <aros@gmx.com>
Cc: Wei Huang <wei.huang2@amd.com>
Tested-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>