iommmu/of: Do not return struct iommu_ops from of_iommu_configure()

iommmu/of: Do not return struct iommu_ops from of_iommu_configure()

Nothing needs this pointer. Return a normal error code with the usual
IOMMU semantic that ENODEV means 'there is no IOMMU driver'.

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/2-v2-16e4def25ebb+820-iommu_fwspec_p1_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>