ARM: dts: am3517-evm: Enable earlycon stdout path

As long as the kernel cmdline has "earlycon" in it, this allows
seeing debug messages earlier and does not require DEBUG_LL to
be enabled.
Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am3517-evm.dts

@@ -20,6 +20,10 @@ aliases {
 		display0 = &lcd0;
 	};
 
+	chosen {
+		stdout-path = &uart3;
+	};
+
 	memory@80000000 {
 		device_type = "memory";
 		reg = <0x80000000 0x10000000>; /* 256 MB */