[SCSI] cciss 2.6 DMA mapping

Patch removes our homegrown DMA masks and uses the ones defined in the kernel.
This patch replaces the broken one I sent in earlier. It has been tested and works. Please discard the first submission.

Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>