arm64: dts: qcom: sc7180-idp: use just "port" in panel

The panel bindings expect to have only one port, thus they do not allow
to use "ports" node:

  sc7180-idp.dtb: panel@0: 'ports' does not match any of the regexes: 'pinctrl-[0-9]+'
  sc7180-idp.dtb: panel@0: 'port' is a required property

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230326155753.92007-4-krzysztof.kozlowski@linaro.org