arm64: dts: imx8mm-venice-gw7904: enable UART1 hardware flow control

On the GW7904 uart1 can use UART3_TX/RX for hardware flow control
which was the desired default configuration. Remove uart3 and configure
uart1 for hardware flow control.
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-venice-gw7904.dts

@@ -636,6 +636,8 @@ &pgc_mipi {
 &uart1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart1>;
+	cts-gpios = <&gpio5 26 GPIO_ACTIVE_LOW>;
+	rts-gpios = <&gpio5 27 GPIO_ACTIVE_LOW>;
 	status = "okay";
 };
 
@@ -646,13 +648,6 @@ &uart2 {
 	status = "okay";
 };
 
-/* off-board RS232 */
-&uart3 {
-	pinctrl-names = "default";
-	pinctrl-0 = <&pinctrl_uart3>;
-	status = "okay";
-};
-
 &usbotg1 {
 	dr_mode = "host";
 	disable-over-current;
@@ -814,6 +809,8 @@ pinctrl_uart1: uart1grp {
 		fsl,pins = <
 			MX8MM_IOMUXC_UART1_RXD_UART1_DCE_RX	0x140
 			MX8MM_IOMUXC_UART1_TXD_UART1_DCE_TX	0x140
+			MX8MM_IOMUXC_UART3_RXD_GPIO5_IO26	0x140 /* CTS# in */
+			MX8MM_IOMUXC_UART3_TXD_GPIO5_IO27	0x140 /* RTS# out */
 		>;
 	};
 
@@ -824,13 +821,6 @@ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX	0x140
 		>;
 	};
 
-	pinctrl_uart3: uart3grp {
-		fsl,pins = <
-			MX8MM_IOMUXC_UART3_RXD_UART3_DCE_RX	0x140
-			MX8MM_IOMUXC_UART3_TXD_UART3_DCE_TX	0x140
-		>;
-	};
-
 	pinctrl_usdhc2: usdhc2grp {
 		fsl,pins = <
 			MX8MM_IOMUXC_SD2_CLK_USDHC2_CLK		0x190