hwmon: use sysfs_emit() to instead of scnprintf()

Replace the open-code with sysfs_emit() to simplify the code.

Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/202212011130317080061@zte.com.cn


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