hwmon: Fix the code examples in documentation

Fix a bug in the code examples, make them comply with CodingStyle,
and indent them for a better redability.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>