dt-bindings: mtd: partitions: add additional example for qcom,smem-part

Add additional example for qcom,smem-part to declare a dynamic
partition to provide NVMEM cells for the commonly ART partition
provided by this parser.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220622010628.30414-3-ansuelsmth@gmail.com