iommu/arm-smmu: Use the flag value when triggering faults

iommu_trigger_fault now passes a flag value when triggering faults.  Use
that value instead of hard-coding a translation fault.

Change-Id: Iac9b97cebef99e260641bde70c1ddfaedd0be502
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>