dt-bindings: display: imx: convert ldb.txt to yaml format

dt-bindings: display: imx: convert ldb.txt to yaml format

Convert ldb.txt to yaml format.

Additional changes
- fix clock-names order to match existed dts file.
- remove lvds-panel and iomuxc-gpr node in examples.
- fsl,imx6q-ldb fail back to fsl,imx53-ldb.
- add fsl,panel property to match existed dts.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250417145742.3568572-1-Frank.Li@nxp.com
[robh: Use #/properties/port schema for port]
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>