hw/arm/smmu-common: Fix devfn computation in smmu_iommu_mr

smmu_iommu_mr() aims at returning the IOMMUMemoryRegion corresponding
to a given sid. The function extracts both the PCIe bus number and
the devfn to return this data. Current computation of devfn is wrong
as it only returns the PCIe function instead of slot | function.

Fixes 32cfd7f3 ("hw/arm/smmuv3: Cache/invalidate config data")

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Message-id: 1530775623-32399-1-git-send-email-eric.auger@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>