we no longer need to add in the offset to the mapped VA to get the correct

we no longer need to add in the offset to the mapped VA to get the correct
device address (bus_tmp, bus_map, and mapiodev now do this for us).

also, we handle all our mappings, so don't have obio.c do any for us
(i.e. don't set ra->ra_len in xycmatch).

nuke uneeded variable in match function.