i2c: Plan i2c-isa for removal

i2c-isa doesn't make much sense in the device driver model. Drivers
relying on it are better implemented as platform drivers. We must
wait for recent versions of libsensors (2.10.0 or later) to be widely
deployed beforehand, though. This move should also make it easier to
convert i2c-core to the device driver model.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>