ARM: dts: porter: Enable SCIF_CLK frequency and pins

Add and enable the external crystal for the SCIF_CLK and its pinctrl, to
be used by the Baud Rate Generator for External Clock (BRG) on (H)SCIF.

This increases the range and accuracy of supported baud rates.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7791-porter.dts

@@ -143,11 +143,19 @@ &extal_clk {
 };
 
 &pfc {
+	pinctrl-0 = <&scif_clk_pins>;
+	pinctrl-names = "default";
+
 	scif0_pins: serial0 {
 		renesas,groups = "scif0_data_d";
 		renesas,function = "scif0";
 	};
 
+	scif_clk_pins: scif_clk {
+		renesas,groups = "scif_clk";
+		renesas,function = "scif_clk";
+	};
+
 	ether_pins: ether {
 		renesas,groups = "eth_link", "eth_mdio", "eth_rmii";
 		renesas,function = "eth";
@@ -221,6 +229,11 @@ &scif0 {
 	status = "okay";
 };
 
+&scif_clk {
+	clock-frequency = <14745600>;
+	status = "okay";
+};
+
 &ether {
 	pinctrl-0 = <&ether_pins &phy1_pins>;
 	pinctrl-names = "default";