Use the atomic state instead, this allows removing plane_config
from the crtc after the full hw readout is completed.

The size can be found in the fb, no need for the plane_config.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NDaniel Stone <daniels@collabora.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>