arm64: dts: rk3399-rock960: add vdd_log and its init value

Add vdd_log node according to rock960 schematic V13.
This patch affect two boards:
- Rock960 Model A
- Ficus

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

arch/arm/dts/rk3399-rock960-u-boot.dtsi

@@ -10,4 +10,17 @@
 	chosen {
 		u-boot,spl-boot-order = &sdhci, &sdmmc;
 	};
+
+	vdd_log: vdd-log {
+		compatible = "pwm-regulator";
+		pwms = <&pwm2 0 25000 1>;
+		regulator-name = "vdd_log";
+		regulator-always-on;
+		regulator-boot-on;
+		regulator-min-microvolt = <800000>;
+		regulator-max-microvolt = <1400000>;
+		regulator-init-microvolt = <950000>;
+		vin-supply = <&vcc5v0_sys>;
+	};
+
 };