dt-bindings: display: bridge: Repurpose lvds-encoder

In an effort to repurpose lvds-encoder.c to also serve the
function of LVDS decoders, we ended up defining a new "generic"
compatible string ("lvds-decoder"), therefore adapt the dt schema
to allow for the new compatible string.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[narmstrong: fixed port descriptions as acked with lpinchart]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1573660292-10629-9-git-send-email-fabrizio.castro@bp.renesas.com