hwmon: (pmbus/zl6100) Add support for ZL2005

Add explicit support for ZL2005. Functionality is almost the same as with other
Zilker Labs / Intersil chips, but limit register detection does not work reliably.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>