hwmon: (nct6683) remove unused variable in nct6683_create_attr_group

When enable 'unused-but-set-variable' compile
warning option, it would raise warning as below:

drivers/hwmon/nct6683.c:415:9:
warning: variable 'j' set but not used [-Wunused-but-set-variable]

Variable 'j' in nct6683_create_attr_group is unused,
so remove it and simplify the 'for' loop.

Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Link: https://lore.kernel.org/r/20220927114352.2498079-1-zengheng4@huawei.com


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