s390x/pci: Set the iommu region size mpcifc request

s390x/pci: Set the iommu region size mpcifc request

The size of the accessible iommu memory region in the guest
is given to the IOMMU by the guest through the mpcifc request
specifying the PCI Base Address and the PCI Address Limit.

Let's set the size of the IOMMU region to:
    (PCI Address Limit) - (PCI Base Address) + 1.

Fixes: f7c40aa1e7 ("s390x/pci: fix failures of dma map/unmap")
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Message-Id: <1547125207-16907-2-git-send-email-pmorel@linux.ibm.com>
Acked-by: Collin Walling <walling@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>