This switches OpenRISC over to fully using the generic dma-mapping
framework.  This was almost already the case as the architecture's
implementation was essentially a copy of the generic header.

This also brings this architecture in line with the recent changes
to dma_map_ops (adding attributes to ops->alloc).

Signed-off-by: Jonas Bonn <jonas@southpole.se>

For the initial architecture submission, not all of the DMA ops were
implemented.  This patch adds the *map_page and *map_sg variants of the
DMA mapping ops.

This patch is currently of interest mainly to some drivers that haven't
been submitted upstream yet.

Signed-off-by: Jonas Bonn <jonas@southpole.se>

Simple DMA implementation.  Allows for allocation of coherent memory
(simply uncached) for DMA operations.

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>