drm/rockchip: lvds: Convert to drm bridge

Convert it to drm bridge driver, it will be convenient for us to
migrate the connector part to the display driver later.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
[on a not-upstream px30 board with lvds display]
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20250526015834.102-1-kernel@airkyi.com