ARM: dts: Use stdout-path in STM32F429 Discovery board

This patch replaces use of linux,stdout-path by stdout-path as per
"chosen" DT bindings documentation.

Doing that, the "console" argument is no more needed in kernel command
line.
Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>

arch/arm/boot/dts/stm32f429-disco.dts

@@ -53,8 +53,8 @@ / {
 	compatible = "st,stm32f429i-disco", "st,stm32f429";
 
 	chosen {
-		bootargs = "console=ttyS0,115200 root=/dev/ram rdinit=/linuxrc";
-		linux,stdout-path = &usart1;
+		bootargs = "root=/dev/ram rdinit=/linuxrc";
+		stdout-path = "serial0:115200n8";
 	};
 
 	memory {