drm/msm: Fix cx collapse issue during recovery

drm/msm: Fix cx collapse issue during recovery

There are some hardware logic under CX domain. For a successful
recovery, we should ensure cx headswitch collapses to ensure all the
stale states are cleard out. This is especially true to for a6xx family
where we can GMU co-processor.

Currently, cx doesn't collapse due to a devlink between gpu and its
smmu. So the *struct gpu device* needs to be runtime suspended to ensure
that the iommu driver removes its vote on cx gdsc.

Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/498398/
Link: https://lore.kernel.org/r/20220819015030.v5.4.I4ac27a0b34ea796ce0f938bb509e257516bc6f57@changeid
Signed-off-by: Rob Clark <robdclark@chromium.org>