arm64: dts: Add uart for mt6797 EVB

This patch adds the pinctrl configuration for the mt6797 EVB.
Signed-off-by: Matthias Brugger <mbrugger@suse.com>

arch/arm64/boot/dts/mediatek/mt6797-evb.dts

@@ -33,4 +33,6 @@ memory@40000000 {
 
 &uart0 {
 	status = "okay";
+	pinctrl-names = "default";
+	pinctrl-0 = <&uart0_pins_a>;
 };

arch/arm64/boot/dts/mediatek/mt6797.dtsi

@@ -142,6 +142,13 @@ pio: pinctrl@10005000 {
 		gpio-controller;
 		#gpio-cells = <2>;
 
+		uart0_pins_a: uart0 {
+			pins0 {
+				pinmux = <MT6797_GPIO234__FUNC_UTXD0>,
+					 <MT6797_GPIO235__FUNC_URXD0>;
+			};
+		};
+
 		uart1_pins_a: uart1 {
 			pins1 {
 				pinmux = <MT6797_GPIO232__FUNC_URXD1>,