arm64: dts: qcom: sm8250: fix display nodes

Apply these fixes to the newly added sm8250 display ndoes
 - Remove "notused" interconnect (which apparently was blindly copied from
   my old patches)
 - Use dispcc node example from dt-bindings, removing clocks which aren't
   documented or used by the driver and fixing the region size.

Fixes: 7c1dffd4

 ("arm64: dts: qcom: sm8250.dtsi: add display system nodes")
Signed-off-by: Jonathan Marek <jonathan@marek.ca>
[DB: compatibility changes split into separate patch]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210329120051.3401567-2-dmitry.baryshkov@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>