drm/sti: make use of drm_of_component_probe

drm/sti: make use of drm_of_component_probe

Enhance the probing sequence by using the ports property of the
display-subsystem node.

That done, it becomes possible to handle the display-substem node
outside of the soc node within the device-tree and not have each IP
blocks as children of the display-subsystem node.

Signed-off-by: Raphael Gallais-Pou <rgallaispou@gmail.com>
Acked-by: Alain Volmat <alain.volmat@foss.st.com>
Link: https://patch.msgid.link/20250717-sti-rework-v1-2-46d516fb1ebb@gmail.com
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>