On some platforms msi parent address regions have to be excluded from
normal IOVA allocation in that they are detected and decoded in a HW
specific way by system components and so they cannot be considered normal
IOVA address space.

Add a helper function that retrieves ITS address regions - the msi
parent - through IORT device <-> ITS mappings and reserves it so that
these regions will not be translated by IOMMU and will be excluded from
IOVA allocations. The function checks for the smmu model number and
only applies the msi reservation if the platform requires it.
Signed-off-by: NShameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
[For the ITS part]
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>