drm: rcar-du: lvds: Get dual link configuration from DT
For dual-LVDS configurations, it is now possible to mark the
DT port nodes for the sink with boolean properties (like
dual-lvds-even-pixels and dual-lvds-odd-pixels) to let drivers
know the encoders need to be configured in dual-LVDS mode.
Rework the implementation of rcar_lvds_parse_dt_companion
to make use of the DT markers while keeping backward
compatibility.