dt-bindings: display: renesas: du: Add vendor prefix to vsps property

The Renesas-specific "vsps" property lacks a vendor prefix.
Add a "renesas," prefix to comply with DT best practises.

Move "renesas,vsps" below "renesas,cmms" to preserve alphabetical sort
order.

Fixes: 06711e63

 ("drm: rcar-du: Document the vsps property in the DT bindings")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>