hwmon: (applesmc) Correct sysfs fan error handling

The current code will not remove the sysfs files for fan numbers three
and up. Also, upon exit, fans one and two are removed regardless of
their existence.  This patch cleans up the sysfs error handling for
the fans.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Jean Delvare <khali@linux-fr.org>