drm/msm/dp: add support of max dp link rate

drm/msm/dp: add support of max dp link rate

By default, HBR2 (5.4G) is the max link rate be supported. This patch
uses the actual limit specified by DT and removes the artificial
limitation to 5.4 Gbps. Supporting HBR3 is a consequence of that.

Changes in v2:
-- add max link rate from dtsi

Changes in v3:
-- parser max_data_lanes and max_dp_link_rate from dp_out endpoint

Changes in v4:
-- delete unnecessary pr_err

Changes in v5:
-- split parser function into different patch

Changes in v9:
-- revised commit test

Changes in v13:
-- repalced "properity" with "property"

Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/516097/
Link: https://lore.kernel.org/r/1672163103-31254-6-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>