dt-bindings: display: bridge: lt9211: Add Lontium LT9211 bridge driver

Add bindings for Lontium LT9211 Single/Dual-Link DSI/LVDS or Single DPI to
Single-link/Dual-Link DSI/LVDS or Single DPI bridge. This chip is highly
capable at converting formats, but sadly it is also highly undocumented.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: devicetree@vger.kernel.org
To: dri-devel@lists.freedesktop.org
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220419143958.94873-1-marex@denx.de