arm: dts: rk3288-evb: set i2c4 clock frequency to 400khz

Change-Id: I849a99d147e9336ba81cd25c92594ffb1289cb53
Signed-off-by: buluess.li <buluess.li@rock-chips.com>

Author: buluess

arch/arm/boot/dts/rk3288-evb.dtsi

@@ -307,6 +307,7 @@
 
 &i2c4 {
 	status = "okay";
+	clock-frequency = <400000>;
 
 	gsl3673@40 {
 		compatible = "GSL,GSL3673";