arm64: dts: qcom: sc7280: Add edp_out port and HPD lines

Like dp_out, we should have defined edp_out in sc7280.dtsi so we don't
need to do this in the board files.

Like dp_hot_plug_det, we should define edp_hot_plug_det in
sc7280.dtsi.

We should set the default pinctrl for edp_hot_plug_det in
sc7280.dtsi. NOTE: this is _unlike_ the dp_hot_plug_det. It is
reasonable that in some boards the dedicated DP Hot Plug Detect will
not be hooked up in favor of Type C mechanisms. This is unlike eDP
where the Hot Plug Detect line (which functions as "panel ready" in
eDP) is highly likely to be used by boards.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220202132301.v3.7.Ic84bb69c45be2fccf50e3bd17b845fe20eec624c@changeid