With new connector model, tc358767 will not create the connector, when
DRM_BRIDGE_ATTACH_NO_CONNECTOR is set and display-controller driver will
rely on format negotiation to setup the encoder format.

Add the missing bus format negotiation hooks in the
drm_bridge_funcs to complete DRM_BRIDGE_ATTACH_NO_CONNECTOR support.

Output format, for DPI/DSI to DP, is selected to
MEDIA_BUS_FMT_RGB888_1X24 as default, keeping in mind what the older
model used to support.
Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Closes: https://lore.kernel.org/all/24282420-b4dd-45b3-bb1c-fc37fe4a8205@siemens.com/Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231108-tc358767-v2-1-25c5f70a2159@ideasonboard.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>