Fix bug #3125:

This should fix the problem; however, we will need to repeat that for all
PIO SCSI drivers (another immediate victim is ppa.c).

We should start looking for sane solution; I _really_ don't like the kludge
with using ->slave_alloc() for fixups after scsi_alloc_queue().
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>