arm64: dts: qcom: sdm845: add displayport node

Add displayport controller device node, describing DisplayPort hardware
block on SDM845.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220810035424.2796777-3-bjorn.andersson@linaro.org