drm/omap: dss: Gather OMAP DSS components at probe time

The omapdss_gather_components() function walks the OF graph to create a
list of all components part of the display device. There's no need to
delay this operation until DSS bind time as we have all the information
we need at probe time.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>