drm/rockchip: vop2: add polarity flags to RGB output

Use h/v-sync and pixel clock polarity flags for RGB output. For all other
outputs this is already implemented.

Signed-off-by: Gerald Loacker <gerald.loacker@wolfvision.net>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230302123949.957998-1-gerald.loacker@wolfvision.net