ARM: dts: imx28: add alternate auart4 pinmux

Add auart4 2-pin configuration on auart0 rts/cts pads.

Signed-off-by: Mans Rullgard <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm/boot/dts/imx28.dtsi

···
 					fsl,pull-up = <MXS_PULL_DISABLE>;
 				};
 
+				auart4_2pins_b: auart4@1 {
+					reg = <1>;
+					fsl,pinmux-ids = <
+						MX28_PAD_AUART0_CTS__AUART4_RX
+						MX28_PAD_AUART0_RTS__AUART4_TX
+					>;
+					fsl,drive-strength = <MXS_DRIVE_4mA>;
+					fsl,voltage = <MXS_VOLTAGE_HIGH>;
+					fsl,pull-up = <MXS_PULL_DISABLE>;
+				};
+
 				mac0_pins_a: mac0@0 {
 					reg = <0>;
 					fsl,pinmux-ids = <