arm64: dts: imx8mq: Fix lcdif compatible

"fsl,imx8mq-lcdif" is compatible to "fsl,imx6sx-lcdif", adjust the list
accordingly. Fixes the dtbs_check warning:
imx8mq-tqma8mq-mba8mx.dtb: lcd-controller@30320000: compatible: 'oneOf'
conditional failed, one must be fixed:
 ['fsl,imx8mq-lcdif', 'fsl,imx28-lcdif'] is too long
 'fsl,imx8mq-lcdif' is not one of ['fsl,imx23-lcdif', 'fsl,imx28-lcdif',
 'fsl,imx6sx-lcdif', 'fsl,imx8mp-lcdif', 'fsl,imx93-lcdif']
 'fsl,imx6sx-lcdif' was expected

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>