IOMMU_CAP_INTR_REMAP has been advertised in arm-smmu(-v3) although
on ARM this property is not attached to the IOMMU but rather is
implemented in the MSI controller (GICv3 ITS).

Now vfio_iommu_type1 checks MSI remapping capability at MSI controller
level, let's correct this.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Will Deacon <will.deacon@arm.com>

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v7 -> v8:
- added Will's A-b