drm/rockchip: Add implicit fencing support for planes

Render like lima will attach a fence to the framebuffer dma_buf,
so the display driver should wait for it to finish before showing
the framebufferto prevent tearing.

Generally tested on rk3188, rk3288, rk3328 and rk3399 and
together with an actual lima-based kmscube on rk3188 and rk3328.

Suggested-by: Qiang Yu <yuq825@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181130102449.6430-1-heiko@sntech.de