- Add missing bus_dmamap_sync(9) calls for the work DMA map. Previously

- Add missing bus_dmamap_sync(9) calls for the work DMA map. Previously
  the work area was totally unsynchronized which means this driver only
  had a chance of working on x86 when no bounce buffers were involved,
  which isn't that likely given that support for 64-bit DMA is currently
  broken throughout ata(4).
- Add necessary little-endian conversion of accesses to the work area,
  making this driver work on big-endian hosts. While at it, use the
  alignment-agnostic byte order encoders in order to be on the safe side.
- Clear the reserved member of the SG list entries in order to be on the
  safe side. [1]

Submitted by:	yongari [1]
Reviewed by:	yongari
Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/stable/8@197488 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f