hwmon: fscher control update bugfix

Here is another small fscher bugfix for 2.6.23 merging, this was caught by Jean
while reviewing my other bugfix. The driver was updating its copy of the
control register as if it was clear to write, but its regular read/write.  This
patch fixes this.

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