* Qualcomm MSM Camera SMMU

[Root level node]
The complete set of context banks for camera are encapsulated under this
root node. Each second level node encapsulates the information related to
the corresponding context bank. During the kernel initialization all
the devices are probed recursively and a device pointer is created for
each context bank keeping track of the virtual address mapping information.

Required properties:
- compatible :
    - "qcom,msm-cam-smmu"

[Second level nodes]
Required properties:
- compatible : one of:
    - "qcom,msm-cam-smmu-cb"
    - "qcom,qsmmu-cam-cb"
- iommus : Handle parsed by smmu driver. Number of entries will vary
  across targets.
- label - string describing iommu domain usage.

Optional properties:
- qcom,scratch-buf-support : Enables iommu scratch buffer support in
  that context bank.

Example:
  qcom,cam_smmu@0 {
    compatible = "qcom,msm-cam-smmu";
    msm_cam_smmu_cb1: msm_cam_smmu_cb1 {
      compatible = "qcom,msm-cam-smmu-cb";
      iommus = <&vfe_iommu 0>;
      label = "vfe";
      qcom,scratch-buf-support;
    }
  }