We introduce a new field to differentiate the reserved region
types and specialize the apply_resv_region implementation.

Legacy direct mapped regions have IOMMU_RESV_DIRECT type.
We introduce 2 new reserved memory types:
- IOMMU_RESV_MSI will characterize MSI regions that are mapped
- IOMMU_RESV_RESERVED characterize regions that cannot by mapped.
Signed-off-by: NEric Auger <eric.auger@redhat.com>
Tested-by: NTomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Tested-by: NBharat Bhushan <bharat.bhushan@nxp.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>