arm64: dts: imx8mq: fix lcdif port node

The port node does not have a unit-address, remove it.
This fixes the warnings:
lcd-controller@30320000: 'port' is a required property
lcd-controller@30320000: 'port@0' does not match any of the regexes:
'pinctrl-[0-9]+'

Fixes: commit d0081bd0 ("arm64: dts: imx8mq: Add NWL MIPI DSI controller")
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>