The brute force iommu_flush_iotlb_all() was good enough for unmap, but
in some cases a map operation could require removing a table pte entry
to replace with a block entry.  This also requires tlb invalidation.
Missing this was resulting an obscure iova fault on what should be a
valid buffer address.

Thanks to Robin Murphy for helping me understand the cause of the fault.

Cc: Robin Murphy <robin.murphy@arm.com>
Cc: stable@vger.kernel.org
Fixes: b145c6e6 ("drm/msm: Add support to create a local pagetable")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/578117/