drm/rockchip: dw_dp: Add DisplayPort support for rk3576

drm/rockchip: dw_dp: Add DisplayPort support for rk3576

The DisplayPort of the RK3576 is basically the same as that of the
RK3588, but it operates in dual-pixel mode and also support MST.

This patch only enable the SST output now.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patch.msgid.link/20260206010421.443605-5-andyshrk@163.com