arm64: dts: imx8mn: Add sound-dai-cells to micfil node

[ Upstream commit db192545 ]

Per the DT bindings, the micfil node should have a sound-dai-cells
entry.

Fixes: cca69ef6 ("arm64: dts: imx8mn: Add support for micfil")
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>