Improve lost-arbitration handling of PCF8584.  This is necessary for
support of a currently out-of-kernel driver for Sun Microsystems E250
environmental management; perhaps others.
Signed-off-by: NEric Brower <ebrower@gmail.com>
Acked-by: NDan Smolik <marvin@mydatex.cz>
Signed-off-by: NJean Delvare <khali@linux-fr.org>