nios2: 10m50: Add CPU pre-relocation in device tree

Tag CPU with dm-pre-reloc to enable driver before
relocation.

Signed-off-by: Gan, Yau Wai <yau.wai.gan@intel.com>
Cc: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Marek Vasut <marex@denx.de>

arch/nios2/dts/10m50_devboard.dts

@@ -19,6 +19,7 @@
 		#size-cells = <0>;
 
 		cpu: cpu@0 {
+			u-boot,dm-pre-reloc;
 			device_type = "cpu";
 			compatible = "altr,nios2-1.1";
 			reg = <0x00000000>;