Patch from Andries.Brouwer@cwi.nl

The following patch does the following:

- static const char *blkdevs[MAX_BLKDEV]; disappears
- get_blkdev_list, (un)register_blkdev, __bdevname
  are moved from block_dev.c to genhd.c
- the third "fops" parameter of register_blkdev was unused;
  now removed everywhere
- zillions of places had printk("cannot get major") upon
  error return from register_blkdev; removed all of these
  and inserted a single printk in register_blkdev.

Of course the reason for the patch is that one fixed size
array is eliminated.