arm64: dts: qcom: sc8280xp-x13s: enable eDP display

Enable the eDP display on MDSS0 DP3, including backlight control.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230111133128.31813-1-johan+linaro@kernel.org