drm/rockchip: vop2: Register the primary plane and overlay plane separately

In the upcoming VOP of rk3576, a Window cannot attach to all Video Ports,
so make sure all VP find it's suitable primary plane, then register the
remain windows as overlay plane will make code easier.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net> # on RK3568
Tested-by: Detlev Casanova <detlev.casanova@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20250303034436.192400-2-andyshrk@163.com