freedreno/drm: Userspace fences

freedreno/drm: Userspace fences

Add a per-fd_pipe fence "timeline" so we can detect cases where we don't
need to call into the kernel to determine if a fd_bo is still busy.

This reuses table_lock, rather than introducing a per-bo lock to protect
fence state updates because (a) the common / hotpath pattern is to
update fences on a lot of objects, but checking the fence state of a
single object is less common, and (b) because we already hold the table
lock in common spots where we need to check the bo's fence state (ie.
allocations from the bo-cache).

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10444>