dt-bindings: panel: lvds: Fix path to display timing bindings

Fixes: 14da3ed8

 ("devicetree/bindings: display: Document common
panel properties")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Rob Herring <robh@kernel.org>