ARM: dts: Add USART1 pin config to STM32F429 boards

This patch selects USART1 pin configuration on PA9/PA10 pins
for both Eval and Disco boards.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>

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

@@ -71,5 +71,7 @@
 };
 
 &usart1 {
+	pinctrl-0 = <&usart1_pins_a>;
+	pinctrl-names = "default";
 	status = "okay";
 };