arm64: dts: qcom: x1e80100-lenovo-yoga-slim7x: add retimers, dp altmode support

comparing with CRD and other dts for a more complete support of the 7X
only retimers, gpios, regulators, dp outputs

Tested-by: Rob Clark <[email protected]>
Tested-by: Jos Dehaes <[email protected]>
Signed-off-by: Jens Glathe <[email protected]>
Reviewed-by: Konrad Dybcio <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Bjorn Andersson <[email protected]>

Author: jglathe