drm/msm/dsi: support CPHY mode for 7nm pll/phy

Add the required changes to support 7nm pll/phy in CPHY mode.

This adds a "qcom,dsi-phy-cphy-mode" property for the PHY node to enable
the CPHY mode.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210617144349.28448-4-jonathan@marek.ca


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>