arm64: dts: imx8mq: Pass address-cells/size-cells to mipi_dsi

mipi_dsi node requires #address-cells and #size-cells.

Pass them to fix the following schema warnings:

imx8mq-mnt-reform2.dtb: mipi-dsi@30a00000: '#address-cells' is a required property
From schema: Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml
imx8mq-mnt-reform2.dtb: mipi-dsi@30a00000: '#size-cells' is a required property
From schema: Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml

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