arm64: dts: ti: k3-am62a7-sk: Fix DDR size to full 4GB

All revisions of AM62A7-SK board have 4GB LPDDR4 Micron
MT53E2G32D4DE-046 AUT:B memory. Commit 38c4a08c ("arm64: dts: ti:
Add support for AM62A7-SK") enabled just 2GB due to a schematics error
in early revision of the board. Fix it by enabling full 4GB available on
the platform.

Design docs: https://www.ti.com/lit/zip/sprr459

Fixes: 38c4a08c ("arm64: dts: ti: Add support for AM62A7-SK")
Signed-off-by: Devarsh Thakkar <devarsht@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Bryan Brattlof <bb@ti.com>
Link: https://lore.kernel.org/r/20230314094645.3411599-1-devarsht@ti.com

arch/arm64/boot/dts/ti/k3-am62a7-sk.dts

@@ -27,8 +27,9 @@ chosen {
 
 	memory@80000000 {
 		device_type = "memory";
-		/* 2G RAM */
-		reg = <0x00000000 0x80000000 0x00000000 0x80000000>;
+		/* 4G RAM */
+		reg = <0x00000000 0x80000000 0x00000000 0x80000000>,
+		      <0x00000008 0x80000000 0x00000000 0x80000000>;
 	};
 
 	reserved-memory {