hwmon: (nct6775-core) Fix overflows seen when writing limit attributes

DIV_ROUND_CLOSEST() after kstrtoul() results in an overflow if a large
number such as 18446744073709551615 is provided by the user.
Fix it by reordering clamp_val() and DIV_ROUND_CLOSEST() operations.

Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Fixes: c3963bc0 ("hwmon: (nct6775) Split core and platform driver")
Message-ID: <7d5084cea33f7c0fd0578c59adfff71f93de94d9.1731375425.git.xiaopei01@kylinos.cn>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>