ARM: dts: rockchip: default serial for rk3288 Tinker Board

The Asus Tinker Board uses serial 2 with 115,200 baud by default for
communication in U-Boot. The same value is also chosen for other RK3288
boards.

So let us set the same value in the Tinker Board device tree.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3288-tinker.dts

@@ -49,6 +49,10 @@ / {
 	model = "Rockchip RK3288 Tinker Board";
 	compatible = "asus,rk3288-tinker", "rockchip,rk3288";
 
+	chosen {
+		stdout-path = "serial2:115200n8";
+	};
+
 	memory {
 		reg = <0x0 0x0 0x0 0x80000000>;
 		device_type = "memory";