iommu/of: Fix check for returning EPROBE_DEFER

Now with IOMMU probe deferral, we return -EPROBE_DEFER
for masters that are connected to an IOMMU which is not
probed yet, but going to get probed, so that we can attach
the correct dma_ops. So while trying to defer the probe of
the master, check if the of_iommu node that it is connected
to is marked in DT as 'status=disabled', then the IOMMU is never
is going to get probed. So simply return NULL and let the master
work without an IOMMU.

Fixes: 7b07cbef ("iommu: of: Handle IOMMU lookup failure with deferred probing or error")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Magnus Damn <magnus.damn@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/of_iommu.c

@@ -118,6 +118,7 @@ static const struct iommu_ops
 
 	ops = iommu_ops_from_fwnode(fwnode);
 	if ((ops && !ops->of_xlate) ||
+	    !of_device_is_available(iommu_spec->np) ||
 	    (!ops && !of_iommu_driver_present(iommu_spec->np)))
 		return NULL;