Merge branch 'v4.14/tracking-qcomlt-iommu' into release/qcomlt-4.14-21022018

* v4.14/tracking-qcomlt-iommu:
  iommu: Check the result of iommu_group_get() for NULL
  iommu/arm-smmu: Add support for qcom,smmu-v2 variant
  iommu/arm-smmu: Add the device_link between masters and smmu
  iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device
  iommu/arm-smmu: Add pm_runtime/sleep ops
  driver core: Delete the link between two given devices
  Revert "arm64/io: Allow I/O writes to use {W,X}ZR"