Merge tag 'iommu-fixes-for-v3.13-rc4' of git://github.com/awilliam/linux-vfio

Pull iommu fixes from Alex Williamson:
 "arm/smmu driver updates via Will Deacon fixing locking around page
  table walks and a couple other issues"

* tag 'iommu-fixes-for-v3.13-rc4' of git://github.com/awilliam/linux-vfio:
  iommu/arm-smmu: fix error return code in arm_smmu_device_dt_probe()
  iommu/arm-smmu: remove potential NULL dereference on mapping path
  iommu/arm-smmu: use mutex instead of spinlock for locking page tables