arm64: zynqmp: Fix DTOVL warning about graphs in kv/kr260

arm64: zynqmp: Fix DTOVL warning about graphs in kv/kr260

DTC is generating warnings about missing port like:
DTOVL   arch/arm/dts/zynqmp-smk-k24-revA-sck-kv-g-revB.dtb
 arch/arm/dts/zynqmp-sck-kv-g-revA.dtbo: Warning (graph_port):
 /fragment@5/__overlay__: graph port node name should be 'port'
...

That's why change description and add it directly to dpsub mode to contain
full description with also port.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/576630cc9696e21bef15bd1f0ca35e396adc4eca.1758529693.git.michal.simek@amd.com