drm/bridge: Drop CONFIG_OF conditionals around of_node pointers

Having conditional around the of_node pointers turns out to make driver
code use ugly #ifdef and #if blocks. So drop the conditionals.

Suggested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230831080938.47454-4-biju.das.jz@bp.renesas.com