hwmon: (nct6775) use sysfs_emit instead of sprintf

hwmon: (nct6775) use sysfs_emit instead of sprintf

Replace sprintf() with sysfs_emit() in sysfs 'show' functions.
sysfs_emit() is preferred because it automatically handles the
buffer size and PAGE_SIZE boundary checks, preventing potential
buffer overflows.

This aligns the legacy code with the new functions in the driver
that already utilize sysfs_emit.

Signed-off-by: Filippo Muscherà <filippo.muschera@gmail.com>
Link: https://lore.kernel.org/r/20260201202721.3871-1-filippo.muschera@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>