SCSI: eata: fix the data buffer accessors conversion regression

commit 20c09df7eb9c92a40e0ecf654b6e8f14c8583b9e upstream.

This fixes the regression introduced by the commit
58e2a02eb18393e76a469580fedf7caec190eb5e (eata: convert to use the
data buffer accessors), reported:

http://marc.info/?t=122987621300006&r=1&w=2

- fix DMA_NONE handling in map_dma()

- this driver can't use scsi_dma_map since host->shost_gendev.parent
is not set properly (it uses scsi_register).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reported-by: Arthur Marsh <arthur.marsh@internode.on.net>
Tested-by: Arthur Marsh <arthur.marsh@internode.on.net>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>