ACPI/IORT: Move the check to get iommu_ops from translated fwspec

With IOMMU probe deferral, iort_iommu_configure can be called
multiple times for the same device. Hence we have a check
to see if the device's fwspec is already translated and return
the iommu_ops from that directly. But the check is wrongly
placed in iort_iommu_xlate, which breaks devices with multiple
sids. Move the check to iort_iommu_configure.

Fixes: 5a1bb638 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error")
Tested-by: Nate Watterson <nwatters@codeaurora.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>