arm64: dts: qcom: sm8250: rename DPU device node

Rename DPU device node to display-controller@ae01000 to follow the
DPU schema.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220708091656.2769390-3-dmitry.baryshkov@linaro.org