media: dt-bindings: media: xilinx: fix typo in example

Fix typo s/:/;/

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>