Add the DU device with a disabled state. Boards that want to enable the
DU need to specify the output topology.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: NMagnus Damm <damm+renesas@opensource.se>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>