arm64: dts: qcom: sc8280xp-crd: Enable EDP

The SC8280XP CRD has a EDP display on MDSS0 DP3, enable relevant nodes
and link it together with the backlight control.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-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/20230111035906.2975494-3-quic_bjorande@quicinc.com