hwmon: Introduce hwmon_device_register_with_groups

hwmon_device_register_with_groups() lets callers register a hwmon device
together with all sysfs attributes in a single call.

When using hwmon_device_register_with_groups(), hwmon attributes are attached
to the hwmon device directly and no longer with its parent device.

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