Now that .init isn't implement anymore we can get rid of it and
do some more cleanup in the scsi device template:

* remove .blk - unused since 2.5.46
* remove .dev_noticed, only midlayer user is gone together with
  .init.  remaining instance now driver-private
* remove .nr_dev and .dev_max - they're purely driver internal
  and at least in sd and sr they'll be completly gone very soon.