arm64: dts: renesas: v3msk: Fix memory size

The V3MSK board has 2 GiB RAM according to the datasheet and schematics.
Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
[geert: Verified schematics]
Fixes: cc3e267e ("arm64: dts: renesas: initial V3MSK board device tree")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210326121050.1578460-1-geert+renesas@glider.be

arch/arm64/boot/dts/renesas/r8a77970-v3msk.dts

@@ -59,7 +59,7 @@ thc63lvd1024_out: endpoint {
 	memory@48000000 {
 		device_type = "memory";
 		/* first 128MB is reserved for secure area. */
-		reg = <0x0 0x48000000 0x0 0x38000000>;
+		reg = <0x0 0x48000000 0x0 0x78000000>;
 	};
 
 	osc5_clk: osc5-clock {