LF-152: ARM64: dts: imx8mq: fix OF graph in imx8mq-evk-dcss-rm67191.dts

LF-152: ARM64: dts: imx8mq: fix OF graph in imx8mq-evk-dcss-rm67191.dts

imx8mq-evk.dts defines a graph connection for hdmi, but
then imx8mq-evk-dcss-rm67191.dts overrides that with a graph
connection for the mipi dsi as the same output signals are used.
This leaves an incomplete graph as the hdmi output has only half a
connection. Though hdmi is disabled in imx8mq-evk-dcss-rm67191.dts
Still have the following warning:

arch/arm64/boot/dts/freescale/imx8mq-evk.dts:1092.21-1094.5:
Warning (graph_endpoint): /soc@0/bus@32c00000/hdmi@32c00000/port@0/endpoint:
graph connection to node '/soc@0/bus@32c00000/
display-controller@32e00000/port@0/endpoint' is not bidirectional

Fix this by delete hdmi node in imx8mq-evk-dcss-rm67191.dts.

Signed-off-by: Sandor Yu <Sandor.yu@nxp.com>
Reviewed-by: Laurentiu Palcu <laurentiu.palcu@nxp.com>