dt-bindings: display: sii902x: Remove trailing white space

Remove trailing white space from sii902x display bridge binding.
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f1f2ef82c4e8ecea920c408bd4e569f5ed27d20a.1558964241.git.jsarha@ti.com