ARM: shmobile: ape6evm-reference: add CPUFreq support

Add CPUFreq support to ape6evm-reference, using a max8973 regulator, that
is supplying V_DVFS for the 4 CA15 cores on r8a73a4.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
diff --git a/arch/arm/boot/dts/r8a73a4-ape6evm-reference.dts b/arch/arm/boot/dts/r8a73a4-ape6evm-reference.dts
index 3251f05..6f4506e 100644
--- a/arch/arm/boot/dts/r8a73a4-ape6evm-reference.dts
+++ b/arch/arm/boot/dts/r8a73a4-ape6evm-reference.dts
@@ -31,3 +31,25 @@
 		ranges = <0 0 0 0x80000000>;
 	};
 };
+
+&i2c5 {
+	vdd_dvfs: max8973@1b {
+		compatible = "maxim,max8973";
+		reg = <0x1b>;
+
+		regulator-min-microvolt = <935000>;
+		regulator-max-microvolt = <1200000>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+};
+
+&cpu0 {
+	cpu0-supply = <&vdd_dvfs>;
+	operating-points = <
+		/* kHz  uV */
+		1950000 1115000
+		1462500  995000
+	>;
+	voltage-tolerance = <1>; /* 1% */
+};