dma-mapping: reliably inform about DMA support for IOMMU
If the DMA IOMMU path is going to be used, the appropriate check should
return that DMA is supported.
Fixes: b5c58b2fdc42 ("dma-mapping: direct calls for dma-iommu") Closes: https://lore.kernel.org/all/181e06ff-35a3-434f-b505-672f430bd1cb@notapiano Reported-by: NĂcolas F. R. A. Prado <nfraprado@collabora.com> #KernelCI Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Tested-by: NĂcolas F. R. A. Prado <nfraprado@collabora.com> Signed-off-by: Christoph Hellwig <hch@lst.de>