arm: mvebu: define and use common Armada XP UART2/3 pinctrl settings

This patch defines common Armada XP pinctrl settings for uart2 and
uart3 interfaces (uart0 and uart1 rx/tx do not rely on MPP):

 uart2: MPP42-43 as default
 uart3: MPP44-45 as default
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Link: https://lkml.kernel.org/r/fd51c080c7139a67ec01df8d797f1e88ce557796.1416613429.git.arno@natisbad.orgSigned-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-xp.dtsi

@@ -55,6 +55,8 @@ i2c1: i2c@11100 {
 
 			uart2: serial@12200 {
 				compatible = "snps,dw-apb-uart";
+				pinctrl-0 = <&uart2_pins>;
+				pinctrl-names = "default";
 				reg = <0x12200 0x100>;
 				reg-shift = <2>;
 				interrupts = <43>;
@@ -65,6 +67,8 @@ uart2: serial@12200 {
 
 			uart3: serial@12300 {
 				compatible = "snps,dw-apb-uart";
+				pinctrl-0 = <&uart3_pins>;
+				pinctrl-names = "default";
 				reg = <0x12300 0x100>;
 				reg-shift = <2>;
 				interrupts = <44>;
@@ -235,4 +239,14 @@ sdio_pins: sdio-pins {
 			       "mpp33", "mpp34", "mpp35";
 		marvell,function = "sd0";
 	};
+
+	uart2_pins: uart2-pins {
+		marvell,pins = "mpp42", "mpp43";
+		marvell,function = "uart2";
+	};
+
+	uart3_pins: uart3-pins {
+		marvell,pins = "mpp44", "mpp45";
+		marvell,function = "uart3";
+	};
 };