arm: zynq: Mark cc108 uart to be initialized before relocation

The same change is done for others zynq boards to get uart as early as
possible.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/dts/zynq-cc108.dts

@@ -100,6 +100,7 @@
 };
 
 &uart0 {
+	u-boot,dm-pre-reloc;
 	status = "okay";
 };