arm64: dts: imx8mq-evk: Add spdif sound card support

There are two spdif IP on imx8mq, spdif1 is for normal
spdif device, spdif2 is for HDMI ARC interface.

Enable these spdif sound card in this patch.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>