hwmon: Introduce hwmon_device_register_for_thermal

The thermal subsystem registers a hwmon driver without providing
chip or sysfs group information. This is for legacy reasons and
would be difficult to change. At the same time, we want to enforce
that chip information is provided when registering a hwmon device
using hwmon_device_register_with_info(). To enable this, introduce
a special API for use only by the thermal subsystem.

Acked-by: Rafael J . Wysocki <rafael@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>