arm64: dts: m3ulcb: Update memory node to 2 GiB map

This patch updates memory region:

  - After changes, the new map of the m3ulcb board on R8A7796 SoC
    Bank0: 1GiB RAM : 0x000048000000 -> 0x0007fffffff
    Bank1: 1GiB RAM : 0x000600000000 -> 0x0063fffffff

  - Before changes, the old map looked like this:
    Bank0: 1GiB RAM : 0x000048000000 -> 0x0007fffffff
Signed-off-by: NVladimir Barinov <vladimir.barinov+renesas@cogentembedded.com>
Tested-by: NSjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796-m3ulcb.dts

@@ -32,6 +32,11 @@
 		reg = <0x0 0x48000000 0x0 0x38000000>;
 	};
 
+	memory@600000000 {
+		device_type = "memory";
+		reg = <0x6 0x00000000 0x0 0x40000000>;
+	};
+
 	leds {
 		compatible = "gpio-leds";