linux-phytec-fsl

drm/sti: fix dynamic z-ordering

Apply the plane depth when the plane is updated.
If the depth is different from the previous plane update,
the register controlling the plane depth is cleaned and updated
with the new depth.

Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>