hwmon_device_register() is deprecated.
Convert driver to use hwmon_device_register_with_info() and
remove sysfs attributes which are now being handled by the
hwmon subsystem.

Channel handling was inspired by corsair-cpro.

Tested on a Fujitsu Esprimo P720.
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210411164225.11967-2-W_Armin@gmx.de
[groeck: Replaced 0 with NULL]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>