This commit introduces a generic device tree binding for
IOMMU devices.  Only a very minimal subset is described
here, but it is enough to cover the requirements of both the
Exynos System MMU and Tegra SMMU as discussed here:

    https://lkml.org/lkml/2014/4/27/346Acked-by: NWill Deacon <will.deacon@arm.com>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NOlof Johansson <olof@lixom.net>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>