drm/tile: expose the tile property to userspace (v3)

This takes the tiling info from the connector and
exposes it to userspace, as a blob object in a
connector property.

The contents of the blob is ABI.

v2: add property + function documentation.

v3: move property setup from previous patch.
add boilerplate + fix long line (Daniel)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 428bb30..7f8c6a6 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -414,6 +414,8 @@
 	intel_dp_add_properties(intel_dp, connector);
 
 	drm_object_attach_property(&connector->base, dev->mode_config.path_property, 0);
+	drm_object_attach_property(&connector->base, dev->mode_config.tile_property, 0);
+
 	drm_mode_connector_set_path_property(connector, pathprop);
 	drm_reinit_primary_mode_group(dev);
 	mutex_lock(&dev->mode_config.mutex);