ACPI/IORT: Do not blindly trust DMA masks from firmware

ACPI/IORT: Do not blindly trust DMA masks from firmware

[ Upstream commit a1df829ead5877d4a1061e976a50e2e665a16f24 ]

Address issue observed on real world system with suboptimal IORT table
where DMA masks of PCI devices would get set to 0 as result.

iort_dma_setup() would query the root complex'/named component IORT
entry for a DMA mask, and use that over the one the device has been
configured with earlier.

Ideally we want to use the minimum mask of what the IORT contains for
the root complex and what the device was configured with.

Fixes: 5ac65e8c8941 ("ACPI/IORT: Support address size limit for root complexes")
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Link: https://lore.kernel.org/r/20210122012419.95010-1-mdf@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>