ARM: dts: imx28-evk: add the RTS/CTS property for auart0

Add the RTS/CTS property for auart0 which means we enable the
DMA support for it.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/boot/dts/imx28-evk.dts

@@ -220,6 +220,7 @@ duart: serial@80074000 {
 			auart0: serial@8006a000 {
 				pinctrl-names = "default";
 				pinctrl-0 = <&auart0_pins_a>;
+				fsl,uart-has-rtscts;
 				status = "okay";
 			};