ARM: dts: sunxi: Remove redundant assigned-clocks

The display backend nodes have an assigned clocks property, while the driver
also enforces it.

Since assigned-clocks is pretty fragile anyway, let's just remove it.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

arch/arm/boot/dts/sun5i.dtsi

@@ -771,9 +771,6 @@
 			interconnect-names = "dma-mem";
 			status = "disabled";
 
-			assigned-clocks = <&ccu CLK_DE_BE>;
-			assigned-clock-rates = <300000000>;
-
 			ports {
 				#address-cells = <1>;
 				#size-cells = <0>;