ARM: dts: sama5d27_wlsom1_ek: enable uart3

Enable uart3. This serial is connected to Mikrobus1 connector.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

Author: ehristev

arch/arm/boot/dts/at91-sama5d27_wlsom1_ek.dts

@@ -17,6 +17,7 @@
 		serial0 = &uart0;	/* DBGU */
 		serial1 = &uart6;	/* BT */
 		serial2 = &uart5;	/* mikro BUS 2 */
+		serial3 = &uart3;	/* mikro BUS 1 */
 		i2c1	= &i2c1;
 	};
 
@@ -177,6 +178,12 @@
 		bias-disable;
 	};
 
+	pinctrl_uart3_default: uart3_default {
+		pinmux = <PIN_PB11__URXD3>,
+			 <PIN_PB12__UTXD3>;
+		bias-disable;
+	};
+
 	pinctrl_usb_default: usb_default {
 		pinmux = <PIN_PA14__GPIO>;
 		bias-disable;
@@ -229,6 +236,14 @@
 	status = "okay";
 };
 
+&uart3 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_uart3_default>;
+	atmel,use-dma-rx;
+	atmel,use-dma-tx;
+	status = "okay";
+};
+
 &usb1 {
 	num-ports = <3>;
 	atmel,vbus-gpio = <0