All non-primary planes get disabled during hw readout,
this reduces complexity and means not having to do some plane
visibility checks during the first commit.
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>