rockchip: px30-evb: remove redundant include file

The file <board name>-u-boot.dtsi inculde automatically by the build
system, no need to add this to dts file.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/dts/px30-evb.dts b/arch/arm/dts/px30-evb.dts
index d886f17..4134e2e 100644
--- a/arch/arm/dts/px30-evb.dts
+++ b/arch/arm/dts/px30-evb.dts
@@ -8,7 +8,6 @@
 #include <dt-bindings/input/input.h>
 #include <dt-bindings/pinctrl/rockchip.h>
 #include "px30.dtsi"
-#include "px30-evb-u-boot.dtsi"
 
 / {
 	model = "Rockchip PX30 EVB";