add support for the global coherent pool to the dma core

[Christoph Hellwig]

Hi all,

this series adds support for using the global coherent (aka uncached)
pool to the generic dma-direct code and then switches arm-nommu and
hexagon over to it, together with a bunch of cleanups.

Diffstat:
 arch/arm/Kconfig                |    5 -
 arch/arm/mm/dma-mapping-nommu.c |  173 +---------------------------------------
 arch/hexagon/Kconfig            |    1 
 arch/hexagon/kernel/dma.c       |   57 ++-----------
 include/linux/dma-map-ops.h     |   18 ++--
 kernel/dma/Kconfig              |    4 
 kernel/dma/coherent.c           |  159 +++++++++++++++++-------------------
 kernel/dma/direct.c             |   15 +++
 8 files changed, 124 insertions(+), 308 deletions(-)