arm64: dts: imx8: split adma ss into dma and audio ss

amda ss is consisted of dma and audio ss in qxp which are
also used in qm.
Let's split them into two ss for better code reuse.

Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>