iommu/exynos: Use first SYSMMU in controllers list for IOMMU core

On Exynos platforms there can be more than one SYSMMU (IOMMU) for one
DMA master device. Since the IOMMU core code expects only one hardware
IOMMU, use the first SYSMMU in the list.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200429133712.31431-31-joro@8bytes.org


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