arm64: dts: renesas: falcon: Complete SCIF0 nodes

SCIF0 has been enabled by the firmware, so it worked already. Still, add
the proper nodes to make it work in any case.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20210121110008.15894-3-wsa+renesas@sang-engineering.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r8a779a0-falcon-cpu.dtsi

@@ -83,6 +83,9 @@ &i2c6 {
 };
 
 &pfc {
+	pinctrl-0 = <&scif_clk_pins>;
+	pinctrl-names = "default";
+
 	avb0_pins: avb0 {
 		mux {
 			groups = "avb0_link", "avb0_mdio", "avb0_rgmii", "avb0_txcrefclk";
@@ -115,8 +118,26 @@ i2c6_pins: i2c6 {
 		groups = "i2c6";
 		function = "i2c6";
 	};
+
+	scif0_pins: scif0 {
+		groups = "scif0_data", "scif0_ctrl";
+		function = "scif0";
+	};
+
+	scif_clk_pins: scif_clk {
+		groups = "scif_clk";
+		function = "scif_clk";
+	};
 };
 
 &scif0 {
+	pinctrl-0 = <&scif0_pins>;
+	pinctrl-names = "default";
+
+	uart-has-rtscts;
 	status = "okay";
 };
+
+&scif_clk {
+	clock-frequency = <24000000>;
+};