drm: renesas: shmobile: Move interface handling to connector setup

Move legacy interface handling to the connector setup code.
Set up bus_flags and bus_formats in display_info according to the
bus format and panel information from platform data, to make it more
similar with DT-based connector/bridge/panel setup.
This will allow us to use the same LCD interface setup code for both
legacy and DT-based systems.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/912f615eb87c847804a268200ab57c63453c65d4.1694767209.git.geert+renesas@glider.be