In the atomic modesetting path, each driver simply wants to grab a ref
to the exclusive fence from a reservation object to store in the incoming
drm_plane_state, without doing the whole RCU dance. Since each driver
will need to do this, lets make a helper.
v2: rename to _rcu instead of _unlocked to be more consistent
Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>