hwmon: (asus_atk0110) Consolidate sysfs attribute initialization

Call sysfs_attr_init() from atk_init_attribute() to handle sysfs attribute
initialization in a single function.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Luca Tettamanti <kronos.it@gmail.com>
Acked-by: Jean Delvare <khali@linux-fr.org>