arm: dts: rockchip: rk3288: update tsadc's working frequence

tsadc in rk3288 can not work well at 10k hz clock. at most time, tsadc
in rk3288 can work well, but it will wrongly report a very high
temperature (eg. 110 degree) occasionally.  we set 5k hz can
resolve this issue.

Change-Id: I06a4a1631baa5f65786a524e2430bb2386f52bdf
Signed-off-by: Rocky Hao <rocky.hao@rock-chips.com>

Author: Rocky Hao

arch/arm/boot/dts/rk3288.dtsi

@@ -572,7 +572,7 @@
 		clocks = <&cru SCLK_TSADC>, <&cru PCLK_TSADC>;
 		clock-names = "tsadc", "apb_pclk";
 		assigned-clocks = <&cru SCLK_TSADC>;
-		assigned-clock-rates = <10000>;
+		assigned-clock-rates = <5000>;
 		resets = <&cru SRST_TSADC>;
 		reset-names = "tsadc-apb";
 		pinctrl-names = "init", "default", "sleep";