Convert to use devm_hwmon_device_register_with_groups to simplify
code and reduce code size. This also attaches sysfs attributes
to the hwmon device and no longer to the platform device.
Tested-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>