We need this to make sure lessees can only connect their
plane/connectors to crtc objects they own. And note that this is
irrespective of whether the lessor is atomic or not, lessor cannot
prevent lessees from enabling atomic.

Cc: stable@vger.kernel.org
Cc: Keith Packard <keithp@keithp.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190228144910.26488-7-daniel.vetter@ffwll.ch