dt-bindings: soc: imx93-media-blk-ctrl: Add PDFC subnode to schema and example

dt-bindings: soc: imx93-media-blk-ctrl: Add PDFC subnode to schema and example

i.MX93 SoC mediamix blk-ctrl contains one DISPLAY_MUX register which
configures parallel display format by using the "PARALLEL_DISP_FORMAT"
field. Document the Parallel Display Format Configuration(PDFC) subnode
and add the subnode to example.

[m.felsch@pengutronix.de: add bus-width]

Signed-off-by: Liu Ying <victor.liu@nxp.com>
[m.felsch@pengutronix.de: port to v6.18-rc1]
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>