On arm64, all SoCs we supported so far either have an IOMMU or have bus
addresses equal to CPU addresses.

However, with the Raspberry Pi 3 coming up, this is no longer true. To
allow DMA to work with an AArch64 kernel on those devices, let's allow
devices to have DMA offsets again.
Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Eric Anholt <eric@anholt.net>