arm64: dts: renesas: r8a774c0: cat874: Add definition for 12V regulator

Power rail "D12.0V" comes straight from the power barrel connector,
and it's used in both main board and sub board.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r8a774c0-cat874.dts

@@ -65,6 +65,15 @@ memory@48000000 {
 		reg = <0x0 0x48000000 0x0 0x78000000>;
 	};
 
+	reg_12p0v: regulator-12p0v {
+		compatible = "regulator-fixed";
+		regulator-name = "D12.0V";
+		regulator-min-microvolt = <12000000>;
+		regulator-max-microvolt = <12000000>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
 	sound: sound {
 		compatible = "simple-audio-card";