phy: qcom: edp: Add set_mode op for configuring eDP/DP submode

Future platforms should not use different compatibles to differentiate
between eDP and DP mode. Instead, they should use a single compatible as
the IP block is the same. It will be the job of the controller to set the
submode of the PHY accordingly.

The existing platforms will remain with separate compatibles for each
mode.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20240324-x1e80100-phy-edp-compatible-refactor-v5-2-a0db5f3150bc@linaro.org


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