arm64: dts: imx8mq-kontron-pitx-imx8m: Use the standard 'uart-has-rtscts'

The usage of the 'fsl,uart-has-rtscts' property is deprecated.

Use the standard 'uart-has-rtscts' instead.

Cc: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: Fabio Estevam <festevam@denx.de>
Acked-By: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-kontron-pitx-imx8m.dts

@@ -311,7 +311,7 @@ &uart2 {
 &uart3 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart3>;
-	fsl,uart-has-rtscts;
+	uart-has-rtscts;
 	assigned-clocks = <&clk IMX8MQ_CLK_UART3>;
 	assigned-clock-parents = <&clk IMX8MQ_SYS1_PLL_80M>;
 	status = "okay";