phy: phy-rockchip-samsung-hdptx: Add eDP mode support for RK3588

phy: phy-rockchip-samsung-hdptx: Add eDP mode support for RK3588

The PHY is based on a Samsung IP block that supports HDMI 2.1, and eDP
1.4b. RK3588 integrates the Analogix eDP 1.3 TX controller IP and the
HDMI/eDP TX Combo PHY to support eDP display.

Add basic support for RBR/HBR/HBR2 link rates, and the voltage swing and
pre-emphasis configurations of each link rate are set according to the
eDP 1.3 requirements.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20250205105157.580060-5-damon.ding@rock-chips.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>