arm64: dts: rockchip: Add nanopi4 bluetooth

Describe the Bluetooth portion of the Ampak combo module - this is
either an AP6356S or an AP6212 depending on the board variant, but
there are no relevant compatibility differences between the two.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>