iommu/of: support iommu configuration for fsl-mc devices

With of_pci_map_rid available for all the busses, use the function
for configuration of devices on fsl-mc bus

Signed-off-by: Nipun Gupta <nipun.gupta@nxp.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>