Revert to fix iommu regression.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/CAF6AEGtvPo4xD2peAztDMPP2n4utb7d9WQboMFwsba9E8U2rCw@mail.gmail.com