arm64: dts: meson-g12: add ATF BL32 reserved-memory region

Add an additional reserved memory region for the BL32 trusted firmware
present in many devices that boot from Amlogic vendor u-boot.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220126044954.19069-3-christianshewitt@gmail.com

arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi

@@ -107,6 +107,12 @@
 			no-map;
 		};
 
+		/* 32 MiB reserved for ARM Trusted Firmware (BL32) */
+		secmon_reserved_bl32: secmon@5300000 {
+			reg = <0x0 0x05300000 0x0 0x2000000>;
+			no-map;
+		};
+
 		linux,cma {
 			compatible = "shared-dma-pool";
 			reusable;