[SCSI] sg: fix incorrect last scatg length

For certain LLDs the sg driver can cause on oops
when the transfer length is large and not a
multiple of PAGE_SIZE.

  ChangeLog:
    - correct the length of the last scatter gather
      list element.
    - fix some printk()s that have the wrong function
      name.

Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>