drm/msm: Stop using iommu_present()

Even if some IOMMU has registered itself on the platform "bus", that
doesn't necessarily mean it provides translation for the device we
care about. Replace iommu_present() with a more appropriate check.

On Qualcomm platforms the IOMMU can be specified either for the MDP/DPU
device or for its parent MDSS device depending on the actual platform.
Check both of them, since that is how both DPU and MDP5 drivers work.

Co-developed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/489699/
Link: https://lore.kernel.org/r/20220616081106.350262-4-dmitry.baryshkov@linaro.org


Signed-off-by: Rob Clark <robdclark@chromium.org>