iommu/amd: Prepare for multiple DMA domain types

The DMA ops reset/setup can simply be unconditional, since
iommu-dma already knows only to touch DMA domains.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/6450b4f39a5a086d505297b4a53ff1e4a7a0fe7c.1628682049.git.robin.murphy@arm.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>