ARM: dts: rockchip: add grf reference in rk3288 tsadc node

The following message can be seen during boot:

  rockchip-thermal ff280000.tsadc: Missing rockchip,grf property

Fix this by adding rockchip,grf property to tsadc node.

The warning itself is not relevant on rk3288 right now, as the
tsadc doesn't need to set GRF-values at this point and only newer
variants do.
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3288.dtsi

@@ -569,6 +569,7 @@ tsadc: tsadc@ff280000 {
 		pinctrl-1 = <&otp_out>;
 		pinctrl-2 = <&otp_gpio>;
 		#thermal-sensor-cells = <1>;
+		rockchip,grf = <&grf>;
 		rockchip,hw-tshut-temp = <95000>;
 		status = "disabled";
 	};