ARM: dts: exynos: Add stdout path property to Arndale board

Replace bootargs and kernel console parameter with 'stdout-path' property
in 'chosen' node to instruct kernel which serial driver should be used
for the kernel console and logs. This allows to enable earlycon messages
by adding just 'earlycon' parameter to kernel command line.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos5250-arndale.dts

@@ -23,7 +23,7 @@ memory@40000000 {
 	};
 
 	chosen {
-		bootargs = "console=ttySAC2,115200";
+		stdout-path = "serial2:115200n8";
 	};
 
 	gpio_keys {