phy: Add Embedded DisplayPort and DisplayPort submodes

In some cases, a DP PHY needs to be configured to work in eDP mode.
So add submodes for both DP and eDP so they can be used by the
controllers for specifying the mode the PHY should be configured in.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240324-x1e80100-phy-edp-compatible-refactor-v5-1-a0db5f3150bc@linaro.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>