Kill all isa-related stuff from i2c_detect, it's not used anymore.

This is one major step in the directiom of merging i2c_probe and
i2c_detect. The last obstacle I can think of is the different way forced
addresses work between sensors and non-sensors i2c drivers. I'll deal
with that in a later patchset.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>