LF-10420-2: arm64: dts: imx8mn: swpdm: add fsl,sai-mclk-direction-output

commit  4f95512483e89fce85526fd92cc482c61164a9e0 from
https://github.com/nxp-imx/linux-imx lf-6.1.y

commit 24bed70a

 ("ASoC: fsl_sai: Revert "ASoC: fsl_sai: Enable
MCTL_MCLK_EN bit for master mode"") remove the enable MCLK out
for master mode in driver.

Need to add fsl,sai-mclk-direction-output property in node.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Chancel Liu <chancel.liu@nxp.com>
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>