ARM: dts: am335x: drop panel endpoint unit address

The endpoint in panel port node should not have unit address:

  am335x-evmsk.dtb: panel: port:endpoint@0: 'reg' is a required property

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20220810130212.400371-1-krzysztof.kozlowski@linaro.org