iommu/tegra-smmu: Pass correct fwnode to iommu_fwspec_init()

iommu_fwspec_init() expects to receive the fwnode corresponding to the
IOMMU device, not the fwnode corresponding to the client device being
probed.

Fix arm_smmu_configure() to pass the correct fwnode to
iommu_fwspec_init().

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/0eec5f84-6b39-43ba-ab2f-914688a5cf45@nvidia.com


Signed-off-by: Will Deacon <will@kernel.org>