To increase the flexibility of supporting different DP main link configuration
at different platform, add both data-lanes and link-frequencies property
into endpoint so that different platform can specify its own main link
combination of both data lanes and max supported link rate.

Changes in v7:
-- split yaml out of dtsi patch
-- link-frequencies from link rate to symbol rate
-- deprecation of old data-lanes property

Changes in v8:
-- correct Bjorn mail address to kernel.org

Changes in v10:
-- add menu item to data-lanes and link-frequecnis

Changes in v11:
-- add endpoint property at port@1

Changes in v12:
-- use enum for item at data-lanes and link-frequencies

Changes in v13:
-- revised changes at port@0
-- use correct ref schemas for both port@0 and port@1
-- mark both port@0 and port@1 are required
-- add line between data-lanes and link-frequencies properties

Changes in v14:
-- add "unevaluatedProperties: false: to endpoint at port@1
-- remove unnecessary quote to $ref
-- re store "$ref: /schemas/graph.yaml#/properties/port" to port@0

Changes in v15:
-- re store desciption of port@0
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/516094/
Link: https://lore.kernel.org/r/1672163103-31254-3-git-send-email-quic_khsieh@quicinc.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>