drm/msm: devcoredump iommu fault support

Wire up support to stall the SMMU on iova fault, and collect a devcore-
dump snapshot for easier debugging of faults.

Currently this is a6xx-only, but mostly only because so far it is the
only one using adreno-smmu-priv.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Jordan Crouse <jordan@cosmicpenguin.net>
Link: https://lore.kernel.org/r/20210610214431.539029-6-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>