hwmon: (abituguru3) Fix I/O error handling

Fix a logic bug reported by Roel Kluin, by rewriting the error
handling code in a clearer way.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Alistair John Strachan <alistair@devzero.co.uk>
Acked-by: Hans de Goede <hdegoede@redhat.com>