spi: rockchip: add bindings for rk3399 spi

Add devicetree bindings for Rockchip rk3399 spi which found on
Rockchip rk3399 SoCs.

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 07909ee9..07c082a 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -866,6 +866,7 @@
 	{ .compatible = "rockchip,rk3066-spi", },
 	{ .compatible = "rockchip,rk3188-spi", },
 	{ .compatible = "rockchip,rk3288-spi", },
+	{ .compatible = "rockchip,rk3399-spi", },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, rockchip_spi_dt_match);