ARM: dts: reduce total RAM by 22 MiB for exynos5422-odroidxu3

Last 22 MiB is RAM is reserved by secure monitor code and cannot be
accessed from Linux kernel, so adjust total RAM size to 0x7EA00000
(2 GiB - 22 MiB). This fixes random 'imprecise kernel abort' kernel
failures.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: NSjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: NKukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos5422-odroidxu3.dts

@@ -18,7 +18,7 @@
 	compatible = "hardkernel,odroid-xu3", "samsung,exynos5800", "samsung,exynos5";
 
 	memory {
-		reg = <0x40000000 0x80000000>;
+		reg = <0x40000000 0x7EA00000>;
 	};
 
 	chosen {