A recent change split iommu_dma_map_msi_msg() in two new functions. The
function was still implemented to avoid modifying all the callers at
once.

Now that all the callers have been reworked, iommu_dma_map_msi_msg() can
be removed.
Signed-off-by: NJulien Grall <julien.grall@arm.com>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Acked-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>