We need to use the inuse count to track that a BO is pinned until
we have the hw_fence.  But we want to remove the obj lock from the
job_run() path as this could deadlock against reclaim/shrinker
(because it is blocking the hw_fence from eventually being signaled).
So split that tracking out into a per-vma lock with narrower scope.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/527839/
Link: https://lore.kernel.org/r/20230320144356.803762-5-robdclark@gmail.com